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Insulin derivatives such as insulin detemir and insulin degludec are U.S. Food and Drug Administration (FDA)-approved long-acting insulin currently used by millions of people with diabetes. These derivatives are modified in C-terminal B29 lysine to retain insulin bioactivity. New and efficient methods for facile synthesis of insulin derivatives may lead to new discovery of therapeutic insulin. Herein, we report a new method using sortase A (SrtA)-mediated ligation for the synthesis of insulin derivatives with high efficiency and functional group tolerance in the C-terminal B chain. This new insulin molecule (Ins-SA) with an SrtA-recognizing motif can be conjugated to diverse groups with N-terminal oligoglycines to generate new insulin derivatives. We further demonstrated that a new insulin derivative synthesized by this SrtA-mediated ligation shows strong cellular and in vivo bioactivity. This enzymatic method can therefore be used for future insulin design and development., Graphical abstract A new method of synthesis of insulin derivatives through sortase A (SrtA) ligation was reported. The insulin substrate (Ins-SA) can be site-selectively modified using sortase A in high efficiency.Image 1

Technological advancements in blood glucose monitoring and therapeutic insulin administration have improved the quality of life for people with type 1 diabetes. However, these efforts fall short of replicating the exquisite metabolic control provided by native islets. We examine the integrated advancements in islet cell replacement and immunomodulatory therapies that are coalescing to enable the restoration of endogenous glucose regulation. We highlight advances in stem cell biology and graft site design, which offer innovative sources of cellular material and improved engraftment. We also cover cutting-edge approaches for preventing allograft rejection and recurrent autoimmunity. These insights reflect a growing understanding of type 1 diabetes etiology, β cell biology, and biomaterial design, together highlighting therapeutic opportunities to durably replace the β cells destroyed in type 1 diabetes.

Proteins and peptides are widely used in various areas including pharmaceutical, health, food, textile and biofuel industries. At present, pharmaceutical proteins and peptides have attracted the attention of many researchers. These types of drugs are superior to chemical drugs in many ways so that every year the number of drugs with a protein or peptide moiety is increasing. Due to high performance and low side effects, the demand for these drugs has increased year by year. The beginning of the protein and peptide drug industry dates back to 1982 with the introduction of the protein hormone insulin into the field of treatment. From this year onwards, a new number of protein and peptide drugs have entered the field of treatment every year. In this article, we focus on human therapeutic insulin. First, the history of the hormone will be introduced, then-current methods for insulin therapy will be discussed and finally, the treatments by this hormone in the future will be pointed. Reading this article would be very helpful for nano researchers, biochemists, organic chemists, material scientists and other people who are interested in soft and hard matters interfaces.

Thyroid-associated ophthalmopathy (TAO) is an autoimmune component of Graves' disease for which no currently available medical therapy provides reliable and safe benefit. Based on insights generated experimentally over the past several decades, the insulin-like growth factor-I receptor (IGF-IR) has been implicated in the pathogenesis of TAO. Furthermore, an IGF-IR inhibitor, teprotumumab, has emerged from 2 clinical trials as a promising treatment for active, moderate to severe TAO. This brief review intends to provide an overview of the rationale underlying the development of teprotumumab for this disease. It is possible that teprotumumab will soon take its place in our therapeutic armamentarium for active TAO.

open access journal People with type 1 diabetes must use insulin and a large fraction of those with type 2 condition also do so. Many therefore struggle with the unpredictable balancing of insulin dose with calorie intake and utility. A healthy pancreas makes meticulous adjustment on a continuous basis that present therapeutic insulin administration cannot match. However, much progress has been made to make it simpler to inject both background and fast-acting boost insulins with a view to better mimicking normal pancreatic output. The present fast insulins are reviewed with accent on the primary amino acid structures of the biosynthetic types that diffuse more quickly than regular insulin that associates in hexamers. This makes boost doses kinetically and clinically more effective, allowing people to inject better estimated boost and corrective doses. Formulation advances are discussed for their present and potential contributions. The newer slow-acting insulins are also described and compared, their advantage also being kinetic with a lower likelihood of inducing overnight hypoglycaemia when used optimally. Finally, the appreciation of the advantages of alternative routes of administration such as oral and peritoneal are included in this review because of the possibility of altering the hepatic to peripheral ratio, the reasons for which are more effective but less obesogenic insulin activity. The logistics of oral insulin are summarised in terms of the risks to the insulin structure, the facilitation of paracellular uptake at the apical surface and the paradoxically advantageous hepatic first pass. Other non-invasive routes are also included in the review.

We thank the Leverhulme Trust (grant no. RPG-2017-214), the Scottish Funding Council (through a St Andrews Restarting Research Fund award) and the Wellcome Trust (through an Institutional Strategic Support Fund award; grant no. 204821/Z/16/Z) for funding. Insulin is stored within the pancreas in an inactive Zn2+-bound hexameric form prior to release. Similarly, clinical insulins contain Zn2+ and form multimeric complexes. Upon release from the pancreas or upon injection, insulin only becomes active once Zn2+ disengages from the complex. In plasma and other extracellular fluids, the majority of Zn2+ is bound to human serum albumin (HSA), which plays a vital role in controlling insulin pharmacodynamics by enabling removal of Zn2+. The Zn2+-binding properties of HSA are attenuated by non-esterified fatty acids (NEFAs) also transported by HSA. Elevated NEFA concentrations are associated with obesity and type 2 diabetes. Here we present the hypothesis that higher NEFA levels in obese and/or diabetic individuals may contribute to insulin resistance and affect therapeutic insulin dose-response profiles, through modulation of HSA/Zn2+ dynamics. We envisage this novel concept to have important implications for personalised treatments and management of diabetes-related conditions in the future. Publisher PDF

The venomous insulin-like peptides released by certain cone snails stimulate hypoglycemic shock to immobilize fish and catch the prey. Compared to human insulin (hIns), the cone snail insulins (Con-Ins) are typically monomeric and shorter in sequence, yet they exhibit moderate human insulin-like biological activity. We have modeled six variants of Con-Ins (G3, K1, K2, T1A, T1B, and T2) and carried out explicit-solvent molecular dynamics (MD) simulations of eight types of insulins, two with known structures (hIns and Con-Ins-G1) and six Con-Ins with modeled structures, to characterize key residues of each insulin that interact with the truncated human insulin receptor (μIR). We show that each insulin/μIR complex is stable during explicit-solvent MD simulations and hIns interactions indicate the highest affinity for the ‘site 1’ of IR. The residue contact maps reveal that each insulin preferably interacts with the αCT peptide than the L1 domain of IR. Through analysis of the average non-bonded interaction energy contribution of every residue of each insulin for the μIR, we probe the residues establishing favorable interactions with the receptor. We compared the interaction energy of each residue of every Con-Ins to the μIR and observed that γ-carboxylated glutamate (Gla), His, Thr, Tyr, Tyr/His, and Asn in Con-Ins are favorable substitutions for GluA4, AsnA21, ValB12, LeuB15, GlyB20, and ArgB22 in hIns, respectively. The identified insulin analogs, although lacking the last eight residues of the B-chain of hIns, bind strongly to μIR. Our findings are potentially useful in designing potent fast-acting therapeutic insulin.

Purpose Exosome-based therapeutic approaches have been applied in diabetes. In the present study, we explored the effect of exosomes on iPSCs differentiation into insulin-producing cells and its underlying mechanisms. Methods Exosomes were isolated by ultracentrifugation from MIN6 cells and identified by Transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and Western blot. PKH67 tracer and transwell assay were used to confirm exosome delivery into iPSCs. QRT-PCR was applied to detect key pancreatic gene expression and miRNAs expression in differentiated iPSCs. Insulin expression was assessed by flow cytometry (FCM) and immunofluorescence. The mechanism underlying exosome induction capacity for iPSCs was determined via RNA-interference of Argonaute-2 (Ago2). Streptozotozin(STZ) was used to establish diabetic mouse model to verify the function of differentiated β-like cells. Results MIN6-derived exosomes promoted the key pancreatic gene expression and immunofluorescence for Nkx6.1 and insulin remarkably, confirming the capability of exosomes for iPSCs differentiation. Moreover, transplantation of differentiated iPSCs efficiently enhanced IPGTT and partially control hyperglycemia in T1D mice. Knockdown of Ago2 in MIN6 cells affect exosomal miRNAs expression and pancreatic gene expression and insulin secretion in iPSCs.The therapeutic effect in vivo was weakened, further indicating decreased exosomal miRNA affect iPSCs differentiation.7 specific exosomal miRNAs were selected for single-assay validation. MiR-706, miR-709, miR-466c-5p and miR-423-5p were found dynamic changed during differentiation stages. Conclusion Exosomes is an effective and convenient induction approach for iPSCs differentiation into functional insulin secreting cells.The effect was downregulated via Ago2 knockdown illustrates the mechanisms are highly relevant to specific miRNAs enriched in exosomes.

Chronically uncontrolled hyperglycemia is the leading cause of end-stage renal disease (ESRD) necessitating dialysis. During times of transition to hemodialysis (HD) or peritoneal dialysis (PD), considerations must be given to insulin dosing adjustments for persons with diabetes (PWD) in efforts to maintain glycemic control. However, literature is sparse with few clear and direct practical clinical recommendations for therapeutic adjustments. The objective of this systematic review was to identify and report the evidence and gaps in the literature for adjustments in therapeutic insulin recommendations when initiating HD or PD in patients with ESRD and diabetes mellitus. A literature search using PubMed, CENTRAL, MEDLINE, CINAHL, Google Scholar, and ClinicalTrials.gov revealed 184 results. After removing duplicates and articles not reaching pre-specified criteria, 29 relevant articles remained for further analysis. The most common recommendation regarding HD was to reduce the basal insulin dose up to 25% on HD days to prevent hypoglycemia, although a lack of consensus exists on the percent reduction. Little information was found as to insulin management with continuous ambulatory PD (CAPD) or automated PD (APD). During PD, insulin may be administered subcutaneously, intraperitoneally, or with the dialysis fluid. Administration of insulin with dialysate may necessitate a dose increase of up to 30% due to a loss to tubing and dilution. Furthermore, the use of dextrose-based dialysate may require additional insulin to mitigate systemic impact of dextrose absorption on blood glucose. Overall, a gap exists in the primary literature regarding recommendations for prophylactically adjusting insulin therapy when initiating HD or PD, or when switching between the two. Greater research is needed to clarify ideal alterations in insulin dosing, administration techniques, and product selections for this patient population. Disclosure R. Tumlinson: None. E. Blaine: None. M. Colvin: None. T. G. Haynes: None. H. P. Whitley: None.

The aim of the review was to analyze the availability of insulin therapy and the ways to improve it in countries with the largest number of patients with diabetes. It was also aimed to assess the medical, social and economic importance of insulin therapy and industrial production of therapeutic recombinant insulin. Materials and methods. The analysis was based on the data taken from monographs and publications in peer-reviewed journals, reports of companies and medical organizations, and the information available in the Internet. The demand and supply in the market of recombinant therapeutic insulin, the insulin market segmentation, and the costs for insulin replacement therapy in countries with the largest number of patients with diabetes were studied. Results and discussion. The pro- and contra- arguments regarding the import of insulin and its impact on the national budget are presented. Technological specifics of recombinant insulin production are discussed; the funding and investments in the biopharmaceutical sector are analyzed. The benefits of industrial production of recombinant therapeutic insulin and its impact on the regional and national economy are demonstrated. Conclusion. The availability of therapeutic insulin in most countries with the largest number of diabetics is unsatisfactory and needs a radical improvement. By analyzing the economic aspects of diabetes and the pharmacoeconomics of insulin, it is advised to develop a modern management system for insulin replacement therapy, especially in countries with large numbers of diabetics. The use of innovative technologies will reduce the production costs of recombinant therapeutic insulin, increase the availability of insulin therapy and thereby improve the quality of life in diabetic patients. Evidence that the production of therapeutic insulin has a positive effect not only on the healthcare, but on the socio-economic situation in the region is also provided. Countries with a number of diabetics exceeding 5 million are encouraged to launch their own production of recombinant therapeutic insulin. The results of the present analysis confirm that half of them are able to manufacture adequate human insulin and/or its analogues.

The significance of the present study is to purify small therapeutic biomolecules such as urea, cobalamin, and insulin of molecular weights below 10 kDa through surface grafted polyethersulfone (PES) ultrafiltration (UF) membranes. The membranes were synthesized by adding an additive of 6 kDa polyethylene glycol (PEG) and grafted with acrylic acid (AA) by varying the concentrations from 2 to 6 wt. % under UV-induce phtocataltic reaction. These membranes were characterized by various tools such as Scanning electron microscope ((SEM), Fourier transforms infrared spectra (FTIR), thermogravimetric analysis (TGA), and contact angle for membrane morphological, structural, thermal stability, and hydrophilicity, respectively. The degree of grafting and their MWCOs of the indigenous membranes were analyzed using various molecular weight solutions of PEG. After PEG doping, the PWF of the membrane was enhanced to 41.50 L m− 2 h− 1 for PES [6+] [0], and a similar trend was also observed for the PEG doped PES grafted membranes. From the experimental results, the synthesized membranes of additive loaded with 5 and 6 wt. % AA grafted PES reject 90 % of the insulin and cobalamin. The results are found to be in correlation with the MWCO values of these membranes ranging from 1 to 10 kDa. From the overall characterization and experimental observations, it can be confirmed that these indigenously synthesized flat sheet grafted membranes showed excellent permeabilities and higher % rejection towards the therapeutic biomolecules.

2021 to 2022 marks the one hundredth anniversary of ground-breaking research in Toronto that changed the course of what was, then, a universally fatal disease: type 1 diabetes. Some would argue that insulin’s discovery by Banting, Best, Macleod, and Collip was the greatest scientific advance of the 20th century, being one of the first instances in which modern medical science was able to provide lifesaving therapy. As with all scientific discoveries, the work in Toronto built upon important advances of many researchers over the preceding decades. Furthermore, the Toronto work ushered in a century of discovery of the purification, isolation, structural characterization, and genetic sequencing of insulin, all of which influenced ongoing improvements in therapeutic insulin formulations. Here we discuss the body of knowledge prior to 1921 localizing insulin to the pancreas and establishing insulin’s role in glucoregulation, and provide our views as to why researchers in Toronto ultimately achieved the purification of pancreatic extracts as a therapy. We discuss the pharmaceutical industry’s role in the early days of insulin production and distribution and provide insights into why the discoverers chose not to profit financially from the discovery. This fascinating story of bench-to-beside discovery provides useful considerations for scientists now and in the future.

Human insulin and its current therapeutic analogs all show propensity, albeit varyingly, to self-associate into dimers and hexamers, which delays their onset of action and makes blood glucose management difficult for people with diabetes. Recently, we described a monomeric, insulin-like peptide in cone snail venom with moderate human-insulin-like bioactivity. Here, with insights from structural biology studies, we report the development of mini-Ins—a human des-octapeptide insulin analog—as a structurally minimal, full-potency insulin. Mini-Ins is monomeric and, despite the lack of the canonical B-chain C-terminal octapeptide, has similar receptor binding affinity to human insulin. Four mutations compensate for the lack of contacts normally made by the octapeptide. Mini-Ins also has similar in vitro insulin signaling and in vivo bioactivities to human insulin. The full bioactivity of mini-Ins demonstrates the dispensability of the PheB24-PheB25-TyrB26 aromatic triplet and opens a novel direction for therapeutic insulin development.

Summary Insulin resistance is a major factor in obesity-linked type 2 diabetes. PPARγ is a master regulator of adipogenesis, and small molecule agonists, termed thiazolidinediones, are potent therapeutic insulin sensitizers. Here, we studied the role of transcriptional co-activator with PDZ-binding motif (TAZ) as a transcriptional co-repressor of PPARγ. We found that adipocyte-specific TAZ knockout (TAZ AKO) mice demonstrate a constitutively active PPARγ state. Obese TAZ AKO mice show improved glucose tolerance and insulin sensitivity compared to littermate controls. PPARγ response genes are upregulated in adipose tissue from TAZ AKO mice and adipose tissue inflammation was also decreased. In vitro and in vivo mechanistic studies revealed that the TAZ-PPARγ interaction is partially dependent on ERK-mediated Ser112 PPARγ phosphorylation. As adipocyte PPARγ Ser112 phosphorylation is increased in obesity, repression of PPARγ activity by TAZ could contribute to insulin resistance. These results identify TAZ as a new factor in the development of obesity-induced insulin resistance.

Measurement of insulin and its therapeutic analogs is important in diabetes, hypoglycemia, sports anti-doping and toxicology. Commercial insulin immunoassays fail to detect commonly prescribed insulin analogs. Because of their unique sequences and masses, these analogs are readily measured and distinguished with mass spectrometric (MS) assays. Reviewed here is an insulin mass spectrometric immunoassay (MSIA) that combines micro-scale immunoaffinity capture with sensitive MS detection of insulin and its therapeutic analogs. An antibody reactive to all insulin analogs was used to affinity capture the insulin analogs. Following elution, insulins were detected with MALDI-TOF MS or LC-MS analysis. Isotopic resolution for insulin was achieved for both MS techniques, and several insulin analogs were detected at unique m/z signals. Porcine insulin, spiked in all samples, served as an internal reference standard for quantification. Linear standard curves spanning three orders of magnitude were obtained, with limits of detection of 15 pM for the MALDI-TOF MS and 1.5 pM for the LC-MS. This insulin assay was capable of detecting and quantifying not only human endogenous insulin, but also most of the therapeutic insulin analogs, which could find use in diagnosis of severe hypoglycemia and in sports anti-doping. Significance Insulin replacement therapy consists of injection of long- or fast-acting insulin analogs with slightly modified primary sequences compared to human insulin. Assays that are capable of detecting all insulin analogs are desired, not only for medical management of diabetes and severe hypoglycemia but also for sports anti-doping and toxicology.

To assess the efficacy of a unified hyperglycemia and diabetic ketoacidosis (DKA) insulin infusion protocol (IIP), based on an Excel algorithm and implemented as an electronic order set, in achieving glycemic targets and minimizing hypoglycemia.An IIP was instituted in medical and surgical intensive care units for post-cardiac surgery (PCS) and other stress hyperglycemia (SH), diabetes hyperglycemia (DH), and DKA. The IIP initiated therapeutic insulin rates at elevated blood glucose (BG), and decreased insulin when target range was achieved. A convenience sample (n=62) was studied; 20 PCS, 15 with DH, 9 with SH, 8 with diabetes on vasopressors, 7 with diabetes on glucocorticoids and 3 with DKA were assessed.The protocol maintained BG at 144±24.7mg/dL for PCS and 167±36mg/dL for patients with diabetes mellitus. It maintained acceptable target range (ATR) (100mg/dL-180mg/dL) 89% of the time for PCS and 67% of the time for patients with diabetes mellitus. There were no measurements of BG70mg/dL. The protocol lowered the BG at a similar rate and time period in those with diabetes, DKA and those with or without vasopressors or glucocorticoids. To determine long-term efficacy, a retrospective review of Point of Care (POC) RALS (Remote Automated Data System) BG data 2 years post implementation demonstrated fewer episodes of hypoglycemia70mg/dL and hyperglycemia240mg/dL and more BG values within ATR.This IIP maintained ATR without hypoglycemia for patients in the ICU setting without requiring complex nursing calculations.

Insulin signaling governs many processes including glucose homeostasis and metabolism, and is therapeutically used to treat hyperglycemia in diabetes. We demonstrated that insulin-induced Akt activation enhances the sensitivity to TGF-β by directing an increase in cell surface TGF-β receptors from a pool of intracellular TGF-β receptors. Consequently, increased autocrine TGF-β signaling in response to insulin participates in insulin-induced angiogenic responses of endothelial cells. With TGF-β signaling controlling many cell responses, including differentiation and extracellular matrix deposition, and pathologically promoting fibrosis and cancer cell dissemination, we addressed to which extent autocrine TGF-β signaling participates in insulin-induced gene responses of human endothelial cells. Transcriptome analyses of the insulin response, in the absence or presence of a TGF-β receptor kinase inhibitor, revealed substantial positive and negative contributions of autocrine TGF-β signaling in insulin-responsive gene responses. Furthermore, insulin-induced responses of many genes depended on or resulted from autocrine TGF-β signaling. Our analyses also highlight extensive contributions of autocrine TGF-β signaling to basal gene expression in the absence of insulin, and identified many novel TGF-β-responsive genes. This data resource may aid in the appreciation of the roles of autocrine TGF-β signaling in normal physiological responses to insulin, and implications of therapeutic insulin usage.

OBJECTIVE Treatment of severe hypoglycemia with loss of consciousness or seizure outside of the hospital setting is presently limited to intramuscular glucagon requiring reconstitution immediately prior to injection, a process prone to error or omission. A needle-free intranasal glucagon preparation was compared with intramuscular glucagon for treatment of insulin-induced hypoglycemia. RESEARCH DESIGN AND METHODS At eight clinical centers, a randomized crossover noninferiority trial was conducted involving 75 adults with type 1 diabetes (mean age, 33 ± 12 years; median diabetes duration, 18 years) to compare intranasal (3 mg) versus intramuscular (1 mg) glucagon for treatment of hypoglycemia induced by intravenous insulin. Success was defined as an increase in plasma glucose to ≥70 mg/dL or ≥20 mg/dL from the glucose nadir within 30 min after receiving glucagon. RESULTS Mean plasma glucose at time of glucagon administration was 48 ± 8 and 49 ± 8 mg/dL at the intranasal and intramuscular visits, respectively. Success criteria were met at all but one intranasal visit and at all intramuscular visits (98.7% vs. 100%; difference 1.3%, upper end of 1-sided 97.5% CI 4.0%). Mean time to success was 16 min for intranasal and 13 min for intramuscular (P < 0.001). Head/facial discomfort was reported during 25% of intranasal and 9% of intramuscular dosing visits; nausea (with or without vomiting) occurred with 35% and 38% of visits, respectively. CONCLUSIONS Intranasal glucagon was highly effective in treating insulin-induced hypoglycemia in adults with type 1 diabetes. Although the trial was conducted in a controlled setting, the results are applicable to real-world management of severe hypoglycemia, which occurs owing to excessive therapeutic insulin relative to the impaired or absent endogenous glucagon response.

It has been >20 years since studies first revealed that the brain is insulin sensitive, highlighted by the expression of insulin receptors in neurons and glia, the presence of circulating brain insulin, and even localized insulin production. Following these discoveries, evidence of decreased brain insulin receptor number and function was reported in both clinical samples and animal models of aging and Alzheimer's disease, setting the stage for the hypothesis that neuronal insulin resistance may underlie memory loss in these conditions. The development of therapeutic insulin delivery to the brain using intranasal insulin administration has been shown to improve aspects of memory or learning in both humans and animal models. However, whether this approach functions by compensating for poorly signaling insulin receptors, for reduced insulin levels in the brain, or for reduced trafficking of insulin into the brain remains unclear. Direct measures of insulin's impact on cellular physiology and metabolism in the brain have been sparse in models of Alzheimer's disease, and even fewer studies have analyzed these processes in the aged brain. Nevertheless, recent evidence supports the role of brain insulin as a mediator of glucose metabolism through several means, including altering glucose transporters. Here, we provide a review of contemporary literature on brain insulin resistance, highlight the rationale for improving memory function using intranasal insulin, and describe initial results from experiments using a molecular approach to more directly measure the impact of insulin receptor activation and signaling on glucose uptake in neurons.

In this article, we examine the nature of the complex relationship between insulin and cardiovascular disease. With metabolic abnormalities comes increased risk for cardiovascular complications. We discuss the key factors implicated in development and progression of cardiovascular disease, its relationship to insulin therapy, and what can be learned from large, recent cardiovascular outcome studies. Preclinical studies suggest that insulin has positive effects of facilitating glucose entry into cells and maintaining euglycemia and negative effects of favoring obesity and atherogenesis under certain conditions. Confounding this relationship is that cardiovascular morbidity is linked closely to duration and control of diabetes, and insulin is often used in patients with diabetes of longer duration. However, more recent clinical studies examining the cardiovascular safety of insulin therapy have been reassuring. Diabetes and cardiovascular outcomes are closely linked. Many studies have implicated insulin resistance and hyperinsulinemia as a major factor for poor cardiovascular outcomes. Additional studies link the anabolic effects of therapeutic insulin to weight gain, along with hypoglycemia, which may further aggravate cardiovascular risk in this population. Though good glycemic control has been shown to improve microvascular risks in type 1 and type 2 diabetes, what are the known cardiovascular effects of insulin therapy? The ORIGIN trial suggests at least a neutral effect of the basal insulin glargine on cardiovascular outcomes. Recent studies have demonstrated that ultra-long-acting insulin analogs like insulin degludec are non-inferior to insulin glargine with regard to cardiovascular outcomes.

Type-2 Diabetes Mellitus (T2DM) is a metabolic syndrome characterized by low insulin sensitivity, so that higher amounts of insulin are required in order to keep glycemia in a safe range (approximately, 60 ~ 110 mg/dl or, equivalently, 3.33 ~ 6.11 mM). Although insulin resistance and T2DM are often treated without exogenous insulin administration, the possibility to early treat pre-diabetic states or T2DM patients with insulin administration could be envisaged if the clinical need exists (e.g. surgical stress, infection). The present work introduces a possible new therapeutic insulin administration dosing approach for T2DM patients. The IVGTT glycemia and insulinemia profiles of a diseased patient are collected and, successively, its metabolic parameters are obtained by fitting a compact delay model to those data. Then a controller is designed exploiting the previous model as a tool. Finally, the tuned controller is applied to the patient as an artificial pancreas supplying external insulin administration. The results are shown on a virtual patient, whose behavior is described by a comprehensive, validated extensive model.

The formation of insulin amyloid can dramatically impact glycemic control in patients with diabetes, making it an important therapeutic consideration. In addition, the cost associated with the excess insulin required by patients with amyloid is estimated to be $3K per patient per year, which adds to the growing financial burden of this disease. Insulin amyloid has been observed with every mode of therapeutic insulin administration (infusion, injection and inhalation), and the number of reported cases has increased significantly since 2002. The new cases represent a much broader demographic, and include many patients who have used exclusively human insulin and human insulin analogs. The reason for the increase in case reports is unknown, but this review explores the possibility that changes in patient care, improved differential diagnosis and/or changes in insulin type and insulin delivery systems may be important factors. The goal of this review is to raise key questions that will inspire proactive measures to prevent, identify and treat insulin amyloid. Furthermore, this comprehensive examination of insulin amyloid can provide insight into important considerations for other injectable drugs that are prone to form amyloid deposits.

The controlled delivery of therapeutics in a manner responsive to physiological indicators has promise in realizing new therapeutic approaches to combat disease. This approach is especially relevant in the context of diabetes. Natural fluctuations in blood glucose seen in the healthy state, complete with peaks and troughs, are poorly regulated as a result of detrimental production or ineffective signaling of the insulin hormone. While several manifestations of diabetes are treated with regularly administered exogenous insulin, the present standard of care results in suboptimal glycemic management that poorly recreates natural hormone control, leading to long-term instability and a significantly increased risk for secondary health complications. New synthetic technologies that make insulin available only when needed, and at the exact dose required, have been explored under the broad vision of realizing a "fully synthetic pancreas." Yet, many challenges remain to realizing a technology that is appropriately responsive, safe, and well integrated into a manageable routine. Herein, many of the approaches explored thus far to sense physiological blood glucose and elicit response through the release of therapeutic insulin are summarized. The approaches point to a new, autonomous approach to managing diabetes with biomimetic therapy.

Hypoglycemia, which occurs commonly during and following exercise in people with diabetes, is thought to be due to attenuated counterregulation in the setting of therapeutic insulin excess. To better understand the pathophysiology of counterregulation, we aimed to determine if dextrose administration to maintain euglycemia during moderate intensity exercise alters the attenuation of counterregulatory responses to subsequent hypoglycemia in healthy adults. Counterregulatory responses to hypoglycemia were assessed in 18 healthy adults after bed rest and following exercise with (n = 9) and without (n = 9) dextrose infusion. Responses were measured during a stepped euglycemic‐hypoglycemic clamp 24 h after either bed rest or two 90‐min bouts of exercise at 70% peak oxygen uptake. Hypoglycemia occurred during the second bout of exercise without dextrose infusion. Plasma glucagon and epinephrine responses to stepped hypoglycemia after antecedent exercise without dextrose infusion were significantly lower at the 45 mg/dL glycemic level compared to after bed rest. However, no attenuation of the counterregulatory responses to hypoglycemia was evident after antecedent exercise when dextrose was infused. This study suggests that the attenuation of the counterregulatory responses during hypoglycemia after exercise is likely due to the hypoglycemia that occurs during moderate prolonged exercise and not solely due to exercise or its intensity.

Therapeutic insulin, in its native and biosynthetic forms as well as several currently available insulin analogues, continues to be the protein of most interest to researchers. From the time of its discovery to the development of modern insulin analogues, this important therapeutic protein has passed through several stages and product generations. Beside the well-known link between diabetes and cancer risk, the currently used therapeutic insulin analogues raised serious concerns due to their potential roles in cancer initiation and/or progression. It is possible that structural variations in some of the insulin analogues are responsible for the appearance of new oncogenic species with high binding affinity to the insulin-like growth factor 1 (IGF1) receptor. The question we are trying to answer in this work is: are there any specific features of the distribution of intrinsic disorder propensity within the amino acid sequences of insulin analogues that may provide an explanation for the carcinogenicity of the altered insulin protein?

Schober E, Wagner G, Berger G, Gerber D, Mengl M, Sonnenstatter S, Barrientos I, Rami B, Karwautz A, Fritsch M, on behalf of the Austrian Diabetic Incidence Study Group. Prevalence of intentional under- and overdosing of insulin in children and adolescents with type 1 diabetes. Objective: The aim of this study was to evaluate the prevalence of insulin under- and overdosing in paediatric patients. Research design and methods: Cross-sectional study including 241 patients (age 14.0 + 2.7 yr, 42.5% males) with type 1 diabetes from 21 diabetic outpatient clinics. Haemoglobin A1c (HbA1c), height, and weight were available from clinical records. Patients were interviewed with the Diabetes Self-Management Profile (DSMP) interview. T test, U test, and chi-squared test were used for comparison. Results: On the basis of the DSMP, 103 (42.7%) patients (group A) showed adherence to the therapeutic insulin regimen, while 71 (29.5%) patients (group B) confessed intentional over and/or under-dosing of insulin. Sixty-seven (27.8%) adolescents (group C) reported management problems leading to unintended inappropriate insulin dosages. In group B, 55 (22.8%) injected higher insulin doses and 58 (24.1%) omitted insulin. Patients of group B compared to group A were older 15.0 (±2.5) vs. 14.0 (±2.5) yr (p < 0.01), older at onset 9.5 (±3.6) vs. 8.3 (±3.8) yr (p = 0.05), were more often girls (69 vs. 45.6%), had a higher actual HbA1c (8.7 ± 1.7 vs. 7.8 ± 1.2%), and a higher average HbA1c in the previous year (8.3 ± 1.6 vs. 7.9 ± 1.2%) (p < 0.01). No significant differences could be found between group A and group C. Conclusion: Intentional overdosing of insulin is almost as prevalent in children and adolescents as insulin omission. Females are more at risk.

The insulin-like growth factor (IGF) axis involves elements of endocrine, paracrine, and autocrine control. It is centrally involved in normal development and growth. Core signaling is driven through the IGF-1 receptor (IGF-1R) in either homo-multimeric complexes or hetero-multimeric complexes with the insulin receptor (IR). Signaling is affected by a large number of upstream and downstream factors, including the differential expression of various intracellular IR substrates, a range of stimulatory ligands (insulin, IGF-1, and IGF-2), the expression of specific clearance receptors (eg, IGF-2R), and different IGF-binding proteins. Considerable evidence exists to implicate aspects of the IGF axis in the development and maintenance of many different nonneoplastic and neoplastic diseases, including both small-cell lung cancer and non-small-cell lung cancer (NSCLC). A large number of different anticancer strategies directed against the IGF axis are being developed. Monoclonal antibodies directed against the IGF-1R are the furthest advanced clinically. Hyperglycemia appears to be a class effect. To date, the major difference among the antibodies used in clinical trials seems to be their plasma half-lives, leading to a number of different administration regimens being taken forward. Early signals of monotherapy activity have been notably reported in patients with Ewing sarcoma and in several other cancers. Encouraging increases in the NSCLC response rate have already been reported after the addition of an anti-IGF-1R antibody to first-line carboplatin and paclitaxel. Explorations of aspects of ligands, binding proteins, receptors, and receptor substrates are all ongoing to identify potential biomarkers predictive of benefit from IGF axis intervention.

Using the micro-scale modification of a newly developed RIA kit for insulin, we established methods for the determination of free and total insulin in serum of insulin-treated diabetics. Precipitation with polyethylene glycol 6000 or acid alcohol extraction of sera was carried out to remove or to dissociate antibody-bound insulin. Both assays permit precise and accurate measurement of either serum insulin fraction. In 50 diabetic sera with tracer insulin binding of 0—97%, free (after equilibration of the sera at 37 °C) and total insulin levels as well as insulin antibody binding parameters were determined. There was a good correlation of free to total insulin levels with maximally 10-fold higher values of total insulin. Both free and total insulin were found to be correlated with the ability of the serum to bind insulin. In detail, binding affinities (i.e. the reciprocal of equilibrium dissociation constants) and binding site concentrations were evaluated which were shown to be positively correlated with free and total insulin levels as well. From these data we conclude that insulin antibodies in the serum may accumulate therapeutic insulin and function as a depot for delivering insulin in insulinopenic episodes (Keilacker et al., 1982 and 1986). Measurement of Insulin in Human Sera Using a New RIA Kit. 1. Insulin Determination in the Absence of Insulin Antibodies — Conventional Assay and Micro Modification

Objective To review the prevalence of, risk factors for, and prevention of hypoglycemia from the perspective of the pathophysiologic aspects of glucose counterregulation in diabetes. Methods This review is based on personal experience and research and the relevant literature. Results Although it can result from insulin excess alone, iatrogenic hypoglycemia is generally the result of the interplay of therapeutic insulin excess and compromised defenses against declining plasma glucose concentrations. Failure of β-cells of the pancreas—early in patients with type 1 diabetes mellitus but later in those with type 2 diabetes mellitus (T2DM)—causes loss of the first 2 physiologic defenses: a decrease in insulin and an increase in glucagon. Such patients are critically dependent on epinephrine, the third physiologic defense, and neurogenic symptoms that prompt the behavioral defense (carbohydrate ingestion). An attenuated sympathoadrenal response to declining glucose levels—caused by recent antecedent hypoglycemia, prior exercise, or sleep—causes hypoglycemia-associated autonomic failure (HAAF) and thus a vicious cycle of recurrent hypoglycemia. Accordingly, hypoglycemia is infrequent early in T2DM but becomes increasingly more frequent in advanced (absolutely endogenous insulin-deficient) T2DM, and risk factors for HAAF include absolute endogenous insulin deficiency; a history of severe hypoglycemia, hypoglycemia unawareness, or both; and aggressive glycemic therapy per se. Conclusion By practicing hypoglycemia risk reduction— addressing the issue, applying the principles of aggressive glycemic therapy, and considering both the conventional risk factors and those indicative of HAAF— it is possible both to improve glycemic control and to minimize the risk of hypoglycemia in many patients. (Endocr Pract. 2008;14:750-756)

Type 2 diabetes mellitus (T2DM) is a complex disease characterized by insulin resistance and a progressive decline in β-cell function and mass. Current evidence suggests that β-cell dysfunction is present early in the course of the disease and that this dysfunction, rather than insulin resistance, is primarily responsible for the progression of T2DM. β-cell dysfunction can be accelerated by glucose toxicity, lipotoxicity, oxidative stress, chronic increases in inflammatory mediators and, potentially, the use of sulfonylureas. This review suggests that future efforts to limit the impact of T2DM must focus on strategies to preserve β-cell function. Several interventions have shown promise in this regard, including lifestyle modifications, thiazolidinediones, potassium channel openers, incretin mimetics, cytokine antagonists, bariatric surgery and dipeptidyl peptidase IV inhibitors, although therapeutic insulin remains the most robust and physiological approach.

Background: Iatrogenic hypoglycemia, the limiting factor in the glycemic management of diabetes mellitus (DM), is the result of therapeutic insulin excess and compromised physiological and behavioral defenses against falling plasma glucose concentrations. Objective: The goal of this article was to review the available evidence on insulin therapy and hypoglycemia, with a focus on type 2 DM. Methods: This review was based on the author's clinical experience, his >3 decades of translational research in the area of hypoglycemia, and his knowledge of the relevant preclinical and clinical literature. Results: Glycemic defenses become compromised rapidly in type 1 DM but slowly in type 2 DM. As a result, the frequency of hypoglycemia increases progressively as patients approach the insulin-deficient end of the spectrum of type 2 DM. Indeed, it appears that most episodes of hypoglycemia, including those of severe hypoglycemia, occur in individuals with type 2 DM. The conventional risk factors for hypoglycemia are based on relative or absolute insulin excess. It is clear that the pathogenesis of hypoglycemia-associated autonomic failure, and thus an increased risk for iatrogenic hypoglycemia, stems fundamentally from insulin deficiency. Relevant additional risk factors include the degree of insulin deficiency, a history of severe hypoglycemia, hypoglycemia unawareness, or both, as well as recent antecedent hypoglycemia, prior exercise and sleep, and aggressive glycemic therapy per se in advanced type 2 DM, just as in type 1 DM. The prevention of hypoglycemia involves the practice of hypoglycemia risk reductionȔdiscussion of the issue, application of the principles of aggressive therapy, and consideration of both the conventional risk factors and those relevant to compromised glycemic defensesȔin advanced type 2 DM, just as in type 1 DM. With this approach, it is possible to improve glycemic control and reduce the frequency of hypoglycemia in many people with DM. Conclusions: Pending the prevention and cure of DM, people with this disease need safe and effective therapies. Ultimately, that will require glucose-regulated insulin replacement or secretion. In the meantime, insight into the mechanisms of hypoglycemia-associated autonomic failure may lead to interventions that will further improve the lives of people affected by DM by reducing the frequency of hypoglycemia without compromising glycemic control.( Insulin. 2007;2:127-133)

Since the discovery of therapeutic insulin in 1922 and the development of the non-obese diabetic spontaneous mouse model in 1980, the establishment of Network for the Pancreatic Organ Donor with Diabetes (nPOD) in 2007 is arguably the most important milestone step in advancing type 1 diabetes (T1D) research. In this perspective, we briefly describe how nPOD is transforming T1D research via procuring and coordinating analysis of disease pathogenesis directly in human organs donated by deceased diabetic and control subjects. The successful precedent set up by nPOD is likely to spread far beyond the confines of research in T1D to revolutionize biomedical research of other disease using high quality procured human cells and tissues.

A sequence of complex conformational changes is required for insulin to bind to the insulin receptor. Recent experimental evidence points to the B chain C-terminal (BC-CT) as the location of these changes in insulin. Here, we present molecular dynamics simulations of insulin that reveal new insights into the structural changes occurring in the BC-CT. We find three key results: 1) The opening of the BC-CT is inherently stochastic and progresses through an open and then a "wide-open" conformation--the wide-open conformation is essential for receptor binding, but occurs only rarely. 2) The BC-CT opens with a zipper-like mechanism, with a hinge at the Phe24 residue, and is maintained in the dominant closed/inactive state by hydrophobic interactions of the neighboring Tyr26, the critical residue where opening of the BC-CT (activation of insulin) is initiated. 3) The mutation Y26N is a potential candidate as a therapeutic insulin analogue. Overall, our results suggest that the binding of insulin to its receptor is a highly dynamic and stochastic process, where initial docking occurs in an open conformation and full binding is facilitated through interactions of insulin receptor residues with insulin in its wide-open conformation.

Delivery of therapeutic insulin via the pulmonary route has been the most investigated non-invasive alternative to the commonly used subcutaneous (SC) route for diabetes management. Despite discontinuation of the first inhalable insulin, Exubera®, due to suboptimal market acceptance, development of orally inhaled insulin delivery systems has been galvanized by the recent approval of Afrezza® and several others awaiting approval.The scope of this review article includes the prospects for and the challenges faced in developing inhaled insulin delivery systems; discussion of orally inhaled therapeutic insulin delivery systems that were discontinued, recently approved or are currently under active investigation; and formulation approaches that have the potential to deliver insulin via the pulmonary route.The pulmonary route is the most advantageous route for non-invasive insulin delivery. Inhalable insulin therapeutics have the potential to be successful, provided that the formulations can be made with modified release patterns to substitute for both prandial and basal insulin injections, the delivery devices are convenient and easy to use, and the long-term safety of inhaled insulin is documented through extensive studies.

Iatrogenic hypoglycemia is a problem for people with diabetes. It causes recurrent morbidity, and sometimes death, as well as a vicious cycle of recurrent hypoglycemia, precluding maintenance of euglycemia over a lifetime of diabetes. Improved therapeutic approaches that will minimize both hypo- and hyperglycemia will be based on insight into the pathophysiology of glucoregulation, specifically glucose counterregulation, in insulin-deficient (type 1 and advanced type 2) diabetes. In such patients, hypoglycemia is the result of the interplay of relative or absolute therapeutic insulin excess and compromised physiological (the syndrome of defective glucose counterregulation) and behavioral (the syndrome of hypoglycemia unawareness) defenses against falling plasma glucose concentrations. The concept of hypoglycemia-associated autonomic failure (HAAF) in diabetes posits that recent antecedent iatrogenic hypoglycemia causes both defective glucose counterregulation (by reducing epinephrine responses to a given level of subsequent hypoglycemia in the setting of absent decrements in insulin and absent increments in glucagon) and hypoglycemia unawareness (by reducing sympathoadrenal and the resulting neurogenic symptom responses to a given level of subsequent hypoglycemia) and thus a vicious cycle of recurrent hypoglycemia. The clinical impact of HAAF is well established in type 1 diabetes; it also affects those with advanced type 2 diabetes. It is now known to be largely reversible, by as little as 2–3 weeks of scrupulous avoidance of hypoglycemia, in most affected patients. However, the mechanisms of HAAF and its component syndromes are largely unknown. Loss of the glucagon secretory response, a key feature of defective glucose counterregulation, is plausibly explained by insulin deficiency, specifically loss of the decrement in intraislet insulin that normally signals glucagon secretion as glucose levels fall. Reduced neurogenic symptoms, a key feature of hypoglycemia unawareness, are largely the result of reduced sympathetic neural responses to falling glucose levels. The mechanism by which hypoglycemia shifts the glycemic thresholds for sympathoadrenal activation to lower plasma glucose concentrations, the key feature of both components of HAAF, is not known. It does not appear to be the result of the release of a systemic mediator (e.g., cortisol, epinephrine) during antecedent hypoglycemia or of increased blood-to-brain glucose transport (although increased transport of alternative fuels is conceivable). It is likely the result of alterations of brain metabolism. Although there is an array of clues, the specific alteration remains to be identified. While the research focus has been largely on the hypothalamus, hypoglycemia is now known to activate widespread brain regions, including the medial prefrontal cortex. The possibility that HAAF could be the result of posthypoglycemic brain glycogen supercompensation has also been raised. Finally, there appear to be diverse causes of HAAF. In addition to recent antecedent hypoglycemia, these include exercise- and sleep-related HAAF. Clearly, a unifying mechanism of HAAF would need to incorporate these causes as well. Pending the prevention and cure of diabetes, critical fundamental, translational, and outcomes research is needed if we are to eliminate hypoglycemia from the lives of people affected by diabetes.

Iatrogenic hypoglycemia is a problem for many people with diabetes (1). It causes recurrent morbidity in most people with type 1 diabetes and many with advanced type 2 diabetes and is sometimes fatal. It generally precludes maintenance of euglycemia over a lifetime of diabetes and therefore full realization of the benefits of glycemic control. It impairs defenses against subsequent falling plasma glucose concentrations and causes a vicious cycle of recurrent hypoglycemia. Hypoglycemia in diabetes is typically the result of the interplay of therapeutic insulin excess—caused by treatment with insulin, a sulfonylurea, or a glinide—and compromised physiological and behavioral defenses against falling plasma glucose concentrations (1,2). Compromised physiological defenses include loss of the normal decrease in β-cell insulin secretion and increase in α-cell glucagon secretion and attenuation of the normal increase in adrenomedullary epinephrine secretion during hypoglycemia. The compromised behavioral defense is failure to ingest carbohydrates because of loss of symptoms due to attenuation of the normal increase in sympathoadrenal, largely sympathetic neural, activity. The concept of hypoglycemia-associated autonomic failure (HAAF) in diabetes posits that recent antecedent hypoglycemia (or sleep or prior exercise) causes both defective glucose counterregulation (by attenuating the epinephrine response in the setting of absent insulin and glucagon responses) and impaired awareness of hypoglycemia (by attenuating sympathoadrenal and the resulting symptomatic responses) and thus a vicious cycle of recurrent hypoglycemia. Although additional intraislet mechanisms may be involved, it is reasonable to attribute both loss of the insulin and of the glucagon responses to hypoglycemia, the prerequisites to HAAF, to β-cell failure. Insulin normally restrains glucagon secretion and a decrease in insulin normally stimulates glucagon secretion during hypoglycemia. In the setting of absolute endogenous insulin deficiency—β-cell failure—there is …

Physiologically, insulin secretion is subject to a dual, hierarchal control by triggering and amplifying pathways. By closing ATP-sensitive K+ channels (KATP channels) in the plasma membrane, glucose and other metabolized nutrients depolarize β-cells, stimulate Ca2+ influx, and increase the cytosolic concentration of free Ca2+ ([Ca2+]i), which constitutes the indispensable triggering signal to induce exocytosis of insulin granules. The increase in β-cell metabolism also generates amplifying signals that augment the efficacy of Ca2+ on the exocytotic machinery. Stimulatory hormones and neurotransmitters modestly increase the triggering signal and strongly activate amplifying pathways biochemically distinct from that set into operation by nutrients. Many drugs can increase insulin secretion in vitro, but only few have a therapeutic potential. This review identifies six major pathways or sites of stimulus-secretion coupling that could be aimed by potential insulin-secreting drugs and describes several strategies to reach these targets. It also discusses whether these perspectives are realistic or theoretical only. These six possible β-cell targets are 1) stimulation of metabolism, 2) increase of [Ca2+]i by closure of K+ATP channels, 3) increase of [Ca2+]i by other means, 4) stimulation of amplifying pathways, 5) action on membrane receptors, and 6) action on nuclear receptors. The theoretical risk of inappropriate insulin secretion and, hence, of hypoglycemia linked to these different approaches is also envisaged.

Native zinc-bound insulin exists as a hexamer at neutral pH. Under destabilizing conditions, the hexamer dissociates, and is very prone to forming fibrils. Insulin fibrils exhibit the typical properties of amyloid fibrils, and pose a problem in the purification, storage, and delivery of therapeutic insulin solutions. We have carried out a systematic investigation of the effect of guanidine hydrochloride (Gdn.HCl)-induced structural perturbations on the mechanism of fibrillation of insulin. At pH 7.4, the addition of as little as 0.25 M Gdn.HCl leads to dissociation of insulin hexamers into dimers. Moderate concentrations of Gdn.HCl lead to formation of a novel partially unfolded dimer state, which dissociates into a partially unfolded monomer state. High concentrations of Gdn.HCl resulted in unfolded monomers with some residual structure. The addition of even very low concentrations of Gdn.HCl resulted in substantially accelerated fibrillation, although the yield of fibrils decreased at high concentrations. Accelerated fibrillation correlated with the population of the expanded (partially folded) monomer, which existed up to6 M Gdn.HCl, accounting for the formation of substantial amounts of fibrils under such conditions. In the presence of 20% acetic acid, where insulin exists as the monomer, fibrillation was also accelerated by Gdn.HCl. The enhanced fibrillation of the monomer was due to the increased ionic strength at low denaturant concentrations, and due to the presence of the partially unfolded, expanded conformation at Gdn.HCl concentrations above 1 M. The data suggest that under physiological conditions, the fibrillation of insulin involves both changes in the association state (with rate-limiting hexamer dissociation) and conformational changes, leading to formation of the amyloidogenic expanded monomer intermediate.

Detecting possible modifications of therapeutic proteins is a critical element of the quality control of protein drugs. Typically, a number of techniques are used to evaluate different modifications of therapeutic protein formulations. Using heteronuclear NMR spectroscopy, we show that the difference between various insulin formulations can be detected "as is" with little pretreatment and quickly. As an application to the quality control of insulin formulations, the NMR approach was compared with four different analytical methods: with reverse phase high pressure liquid chromatography (HPLC) (for mutations), with size exclusion chromatography (for oligomerization), with electrophoresis (for denaturation), and with mass spectrometry (for deamidation). All of the results showed that this single NMR method can provide the specific signatures for each modification and information that is at least equivalent to that offered by the conventional analytical methods. Importantly, NMR could yield information at each amino acid residue level which no other technique provided. The suggested NMR method, then, can be considered to be a facile and effective means of evaluating therapeutic protein formulations in a multifaceted way.

The most ubiquitous treatment strategy for DM focuses on the control of postprandial blood glucose, i.e. glucose level after food intake. The goal of an exogenous insulin regimen in diabetics is to mimic the physiological profile observed in a healthy person (non-diabetic). In the past few years, there has been a great deal of interest and research worldwide in the development of non-invasive routes for delivery of insulin. Various routes of administration have been explored to avoid regular dependence on multiple subcutaneous injections and to improve the metabolic effects of insulin. The objective of this chapter is to provide an update on the various approaches that have been explored so far to achieve therapeutic insulin levels using non-invasive drug delivery routes.

Non-Therapeutic Insulin Use in Resistance-Trained Men Limited evidence exists detailing the ergogenic use of nontherapeutic insulin. This study sought to further clarify the nontherapeutic insulin use in resistance-trained men using the validated, 37-item, Strength Training Ergogenic Survey (STES). Self-selected subjects completed the Internet-based STES. The final sample included 199 male, non-type I diabetic, respondents. Of all respondents, 27.1% used non-therapeutic insulin, all but one of whom also used anabolic-androgenic steroids (98.1%). Those using non-therapeutic insulin were older, bigger, had greater annual incomes, and trained longer, when compared to non-users. Users were more likely European as well as being participants in either bodybuilding or powerlifting. Most believed some of their competitor’s used non-therapeutic insulin. Over four-in-five (81.5%) of non-therapeutic insulin users administered the drug after training and almost all (94.4%) administered it in a cyclic fashion. Reasons cited for non-therapeutic insulin use included: improve physique (84.2%), improve muscle mass (73.3%, and decrease fat (67.9%). Polypharmacy was the norm among non-therapeutic insulin users, as almost all (91.0%) respondents also abused anabolic-androgenic steroids or other drugs. The current study substantiates nontherapeutic insulin use by this sample of resistance trained males, with unknown, but potentially negative, health consequences. Non-therapeutic insulin use is a relevant issue for strength and conditioning specialists, fitness professionals, and healthcare practitioners. The non-therapeutic use of insulin may be increasing, necessitating a better understanding by all concerned, as well as further study by researchers.

Hypoglycemia is the limiting factor in the glycemic management of diabetes because it generally precludes maintenance of euglycemia. Improving glycemic control while minimizing hypoglycemia in type 1 diabetes mellitus (T1 DM) involves both application of the principles of aggressive therapy--patient education and empowerment, frequent self monitoring of blood glucose, flexible insulin regimens, individualized glycemic goals and ongoing professional guidance and support--and implementation of hypoglycemia risk reduction. Iatrogenic hypoglycemia is the result of the interplay of therapeutic insulin excess and compromised physiological and behavioral defenses against falling plasma glucose concentrations in T1 DM. Relative or absolute insulin excess occurs when insulin doses are excessive, ill-timed or of the wrong type, when exogenous glucose delivery, endogenous glucose production or insulin clearance are decreased or when insulin-independent glucose utilization or sensitivity to insulin are increased. But these conventional risk factors explain only a minority of episodes of severe hypoglycemia. More potent risk factors include absolute insulin deficiency, a history of severe hypoglycemia and aggressive therapy per se as evidenced by lower glycemic goals, lower hemoglobin A1c levels, or both. These are clinical surrogates of compromised glucose counterregulation, the clinical syndromes of defective glucose counterregulation (the result of absent decrements in insulin and absent increments in glucagon with attenuated increments in epinephrine) and hypoglycemia unawareness (the result of reduced autonomic [sympathochromaffin] activation causing reduced warning symptoms of developing hypoglycemia). The unifying concept of hypoglycemia-associated autonomic failure in T1 DM posits that: (1) Periods of relative or absolute therapeutic insulin excess in the setting of absent glucagon responses lead to episodes of hypoglycemia. (2) These episodes, in turn, cause reduced autonomic (including adrenomedullary) responses to falling glucose concentrations on subsequent occasions. (3) These reduced autonomic responses result in both reduced symptoms of developing hypoglycemia (i.e., hypoglycemia unawareness) and--because epinephrine responses are reduced in the setting of absent glucagon responses--impaired physiological defenses against developing hypoglycemia (i.e., defective glucose counterregulation). Thus a vicious cycle of recurrent hypoglycemia is created and perpetuated. Hypoglycemia risk reduction includes, first, addressing the issue of hypoglycemia--the patient's awareness of and concerns about it, its frequency, severity, timing and clinical settings--in every patient contact. Then it requires application of the principles of aggressive therapy, consideration of both the conventional risk factors and those indicative of compromised glucose counterregulation and appropriate regimen adjustments including a two to three week period of scrupulous avoidance of hypoglycemia in patients with hypoglycemia-associated autonomic failure. With this approach the goals of improving glycemic control and minimizing hypoglycemia are not incompatible.

Insulin analogues represent a major and growing class of biotherapeutics, and their quantitation is an important focus of commercial and public effort across a number of different fields. As LC–MS has developed, it has become an increasingly practicable and desirable alternative to ligand-binding-based approaches for quantitation of this class of compounds. The sensitivity challenge of measuring trace levels of this large peptide molecule in a protein-containing matrix is considerable; however, different approaches to detection, extraction and separation are described to overcome this challenge, including immunoaffinity capture, SPE and low-flow HPLC. Considerations such as bioanalytical assay acceptance criteria and antidrug antibody effects during drug development are included, alongside descriptions of recent sports doping and clinical applications. Factors affecting the correlation and agreement of MS with biological ligand-binding methods are discussed, with ways to anticipate and appreciate differences between the values derived from each technique. The ‘future perspective’ section discusses the likely trend towards MS-based analysis for these compounds and the impact of HRMS. A high degree of scientific creativity, combined with science-defined regulatory approaches that define suitable validation criteria, will be needed to meet the demanding requirements for high-throughput analysis of insulin by LC–MS.

BACKGROUND Hepatic glucose-6-phosphatase activity is low at birth, and in term infants rises rapidly to adult levels. In contrast, in most preterm infants, it remains low postnatally making them vulnerable to repeated hypoglycaemic episodes, resultant cerebral damage, or risk of sudden and unexpected death. AIMS To investigate the clinical features of preterm infants with low glucose-6-phosphatase enzyme activity to determine the influencing factors. METHODS Clinical data from 36 preterm infants were correlated by stepwise multiple regression analysis with V max of hepatic glucose-6-phosphatase as the dependent variable. RESULTS The most significant correlation was with the administration of insulin (units/kg/h postnatal life) with lesser effects of respiratory distress syndrome and dopamine administration. The V max changes reflected changes in the level of expression of the glucose-6-phosphatase protein. CONCLUSION In a variety of animal models, hepatic glucose-6-phosphatase levels have been shown to decrease in response to insulin, which also decreases transcription of the glucose-6-phosphatase gene. The association of insulin administration with high levels of hepatic glucose-6-phosphatase activity and protein expression was therefore most unexpected. Results from model systems, or adults, must be extrapolated to the metabolism of preterm infants with caution.

Insulin receptor signalling has a central role in mammalian biology, regulating cellular metabolism, growth, division, differentiation and survival1,2. Insulin resistance contributes to the pathogenesis of type 2 diabetes mellitus and the onset of Alzheimer’s disease3; aberrant signalling occurs in diverse cancers, exacerbated by crosstalk with the homologous type 1 insulin-like growth factor receptor (IGF1R)4. Despite more than three decades of investigation, the three-dimensional structure of the insulin–insulin receptor complex has proved elusive, confounded by the complexity of producing the receptor protein. Here we present the first view, to our knowledge, of the interaction of insulin with its primary binding site on the insulin receptor, on the basis of four crystal structures of insulin bound to truncated insulin receptor constructs. The direct interaction of insulin with the first leucine-rich-repeat domain (L1) of insulin receptor is seen to be sparse, the hormone instead engaging the insulin receptor carboxy-terminal α-chain (αCT) segment, which is itself remodelled on the face of L1 upon insulin binding. Contact between insulin and L1 is restricted to insulin B-chain residues. The αCT segment displaces the B-chain C-terminal β-strand away from the hormone core, revealing the mechanism of a long-proposed conformational switch in insulin upon receptor engagement. This mode of hormone–receptor recognition is novel within the broader family of receptor tyrosine kinases5. We support these findings by photo-crosslinking data that place the suggested interactions into the context of the holoreceptor and by isothermal titration calorimetry data that dissect the hormone–insulin receptor interface. Together, our findings provide an explanation for a wealth of biochemical data from the insulin receptor and IGF1R systems relevant to the design of therapeutic insulin analogues.

New generations of drugs are using more and more often therapeutic proteins as the active ingredient, prompting the regulation agencies to adapt their analytical methods. Fast and unambiguous information on the secondary, tertiary and quaternary structure of the protein should be provided to assess the quality of these biodrugs. Recent developments of heteronuclear NMR methods, enabling their use on pharmaceutical formulated unlabeled proteins, provide an efficient way to perform such analysis, a feature that is illustrated here using various commercial formulations of insulins.

We have previously reported that the absence of leptin signaling in β-cells enhances glucose-stimulated insulin secretion and improves glucose tolerance in vivo. To investigate the relevance of β-cell leptin signaling in the context of postprandial or therapeutic insulin secretion, we examined the cross talk between leptin and glucagon-like peptide (GLP)-1 and sulfonylurea actions. Single and size-matched islets isolated from control or pancreas-specific leptin receptor knockout (pancreas-ObR-KO) mice were treated either with GLP-1 or with glibenclamide. Leptin suppressed GLP-1-stimulated intracellular Ca(2+) concentrations ([Ca(2+)](i)) increase that paralleled the decrease in insulin secretion in controls. In contrast, and as expected, the ObR-KO islets were nonresponsive to leptin, and instead, showed a 2.8-fold greater GLP-1-stimulated [Ca(2+)](i) increase and a 1.7-fold greater insulin secretion. Phosphorylation of cAMP-responsive element binding protein was enhanced, and phosphodiesterase enzymatic activity was suppressed in MIN6 β-cells with ObR knockdown compared with controls. The ObR-KO islets also showed significantly higher glibenclamide-induced insulin secretion compared with control islets, whereas [Ca(2+)](i) was similar to the controls. These data support enhanced insulinotropic effects of glucose, GLP-1, and sulfonylureas in the islets lacking leptin signaling with potential therapeutic implications.

Iatrogenic hypoglycemia is the limiting factor in the management of insulin-dependent diabetes mellitus (IDDM). It causes recurrent physical morbidity, some mortality, and recurrent or even persistent psychosocial morbidity. The principles of glucose counterregulation, the physiological mechanisms that normally very effectively prevent or correct hypoglycemia, are now known. Decrements in insulin, increments in glucagon, and, in the absence of the latter, increments in epinephrine stand high in the hierarchy of redundant glucose counterregulatory factors. Iatrogenic hypoglycemia in IDDM is the result of the interplay of absolute or relative therapeutic insulin excess and compromised glucose counterregulation. Syndromes of compromised glucose counterregulation include defective glucose counterregulation (the result of combined deficiencies of the glucagon and epinephrine responses to falling glucose levels), hypoglycemia unawareness (loss of the warning, neurogenic symptoms of developing hypoglycemia), and elevated glycemic thresholds (lower glucose levels required) for autonomic activation and symptoms during effective intensive therapy. These have been conceptualized as examples of hypoglycemiaassociated autonomic failure, a functional disorder distinct from classical diabetic autonomic neuropathy, in IDDM. Recent antecedent iatrogenic hypoglycemia appears to be a major factor in the pathogenesis of hypoglycemia unawareness; there is increasing evidence that this syndrome is reversible with scrupulous avoidance of hypoglycemia. It probably also contributes substantially to the syndrome of elevated glycemic thresholds during intensive therapy. However, factors in addition to recent antecedent hypoglycemia play an important role in the pathogenesis of the syndrome of defective glucose counterregulation. Pending the prevention and cure of IDDM, we need to learn to replace insulin in a much more physiological fashion and/or to prevent, correct, or compensate for compromised glucose counterregulation if we are to eliminate hypoglycemia from the lives of people with IDDM without compromising glycemic control. In the meantime, we must continue to seek better insight into the fundamental mechanisms of compromised glucose counterregulation and to develop practical preventive clinical strategies and practice hypoglycemia risk factor reduction with our patients.

Whilst insulin is a spectacularly successful drug for the management of diabetes mellitus, it remains difficult to mimic the physiological pattern of insulin secretion, even using the various quick-acting and insoluble formulations that are available. The introduction of recombinant-DNA technology to the manufacture of therapeutic insulin has made the rational design and production of insulin analogues with altered pharmacokinetic and pharmacological properties possible. Such analogues include 'monomeric' insulins, which do not form the insulin-zinc hexamer in solution and are absorbed more rapidly from the injection site, and long-acting insulins, which are absorbed very slowly at physiological pH. Many of these analogues are being tested clinically, and it is possible that the next generation of insulin therapy will be various combinations of rationally designed insulin analogues produced by industrial biotechnology.

This report is an analysis of neurological and psychiatric manifestations observed in 27 patients suffering from verified adenoma of the islet cell apparatus of the pancreas. In addition relevant laboratory data, mainly those related to the glucose metabolism and in the last 11 patients also the EEG findings are discussed. The clinical data were arranged in four groups: (1) autonomic-visceral, (2)somatic-neurological, (3) "psychomotor" manifestations and (4) seizures and seizure fragments. These four groups of data are then discussed in terms of anatomic-physiological levels using concepts established by Himwich. Our findings differ in several important aspects from those found in therapeutic insulin shock. An attempt is made to understand the reasons for this divergence. Glucose tolerance curves in a majority of our cases are diabetic in pattern and often also in level. "Flat" curves are the exception in our experience. The EEG findings are those to be expected in patients whose cerebral metabolism is de...