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Aim: The study aimed to compare the effectiveness of oral hypoglycemic agents (OHAs) as monotherapy, dual and quadruple therapy for glycemic control (GC) and glycemic variability (GV) in patients with type 2 diabetes (T2DM) using flash glucose monitoring system (FGM)., Background: Diabetes management largely relies on HbA1c monitoring. Glycemic variability has been an evolving glycemic target for preventing complications related to type 2 diabetes mellitus., Objective: The purpose of the study was to compare glycemic control measures and glycemic variability measures among study groups and to study the relationships between GC and GV indices., Methods: Retrospectively, FGM data were collected from 50 T2DM patients. The patients were classified based on prescribed number of OHAs as monotherapy [group 1: Dipeptidyl peptidase- 4 (DPP-4) inhibitors (n=10), group 2: Sodium-glucose co-transporter-2 (SGLT2) inhibitors (n=10), group 3: Sulphonylureas (n=10), group 4: Dual therapy (n=10), and group 5: Quadruple therapy (n=10)]. Measures of GC and GV were evaluated., Results: Significant differences between study groups were observed in GC and GV measurements. The SGLT2 inhibitors monotherapy group demonstrated optimal GC [eA1c (%): 6.5 ± 2.2; MBG: 140.80 ± 63.94; TIR: 60.60 ± 19.96] and GV (SD: 42.38 ± 34.57; CV: 27.85 ± 6.68; MAGE: 96.76 ± 52.47; MODD: 33.96 ± 22.91) in comparison to other study groups. On using Pearson correlation analysis, mean blood glucose (MBG) and mean amplitude of glycemic excursion (MAGE) showed moderate correlation (r = 0.742)(r 2 = 0.551), depicting distinct glucose variabilities at the same mean blood glucose levels., Conclusion: The monotherapy group of SGLT2 inhibitors demonstrated glucose-lowering effects with reduced glycemic variability. Hence, optimum glycemic control is associated with decreased glycemic variability.

Diabetes is a metabolic disorder that has been reported to increase the mortality rate worldwide. About 40 million people across the globe suffer from diabetes, with people living in developing countries being affected the most due to this deadly disease. Although the therapeutic management of hyperglycaemia can treat diabetes, metabolic disorders associated with this disease are a greater challenge in its treatment. Hence, potential strategies to treat hyperglycaemia and its side effects are needed. In this review, we have summarized several therapeutic targets, like dipeptidyl peptidase-4 (DPP-4), glucagon receptor antagonists, glycogen phosphorylase or fructose-1,6- biphosphatase inhibitors, SGLT inhibitors, 11beta-HSD-1 inhibitors, glucocorticoids receptor antagonists, glucose-6-phosphatase and glycogen phosphorylase inhibitors. These targets can help in designing and developing novel antidiabetic agents., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Diabetes is a chronic metabolic disorder. According to the International Diabetes Federation, about 537 million people are living with diabetes. The two types of diabetes are type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM), among which the population affected by T2DM is relatively higher. A major reason for T2DM is that insulin stimulation is hampered due to the inactivation of incretin hormones. Dipeptidyl peptidase-IV (DPP-IV) is a serine protease that is directly involved in the inactivation of incretin hormones, e.g., glucagon-like peptide-1 (GLP-1). Therefore, the inhibition of DPP-IV can be a promising method for managing T2DM, in addition to other enzyme inhibition strategies, such as inhibition of α-amylase and α -glucosidase. Currently, about 12 different gliptin drugs are available in the market that inhibit DPP-IV in a dose-dependent manner. Instead of gliptins, 'peptides' can also be employed as an alternative and promising way to inhibit DPP-IV. Peptide inhibitors of DPP-IV have been identified from various plants and animals. Chemically synthesized peptides have also been experimented for inhibiting DPP-IV. Most peptides have been analysed by biochemical assays, whereas some in vitro assays have also been reported. Molecular docking analysis has been applied to comprehend the mechanism of inhibition. In this review, certain aspects of natural as well as synthetic peptides are described that have been proven to inhibit DPP-IV., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in individuals with diabetes mellitus (DM). Although benefit has been attributed to the strict control of hyperglycemia with traditional antidiabetic treatments, novel antidiabetic medications have demonstrated cardiovascular (CV) safety and benefits by reducing major adverse cardiac events, improving heart failure (HF), and decreasing CVD-related mortality. Emerging data underline the interrelation between diabetes, as a metabolic disorder, and inflammation, endothelial dysfunction, and oxidative stress in the pathogenesis of microvascular and macrovascular complications. Conventional glucose-lowering medications demonstrate controversial CV effects. Dipeptidyl peptidase- 4 inhibitors have not only failed to prove to be beneficial in patients with coronary artery disease, but also their safety is questionable for the treatment of patients with CVD. However, metformin, as the first-line option for type 2 DM (T2DM), shows CVD protective properties for DM-induced atherosclerotic and macrovascular complications. Thiazolidinedione and sulfonylureas have questionable effects, as evidence from large studies shows a reduction in the risk of CV events and deaths, but with an increased rate of hospitalization for HF. Moreover, several studies have revealed that insulin monotherapy for T2DM treatment increases the risk of major CV events and deaths from HF, when compared to metformin, although it may reduce the risk of myocardial infarction. Finally, this review aimed to summarize the mechanisms of action of novel antidiabetic drugs acting as glucagon-like peptide-1 receptor agonists and sodium-glucose co-transporter-2 inhibitors that show favorable effects on blood pressure, lipid levels, and inflammation, leading to reduced CVD risk in T2DM patients., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Recent reports suggest that prediabetes is a risk factor for developing severe COVID-19 complications through underlying mechanisms involving undiagnosed sub-clinical inflammation. However, we remain without a clinical approach for managing COVID-19 in prediabetic cases. The subclinical inflammation in prediabetes is associated with elevated DPP4 levels and activity. DPP4 has pleiotropic actions, including glycaemia regulation and immuno-modulation. Recently, DPP4 has been recognised as a co-receptor for COVID-19 for entering host cells. In addition to improving glycaemia, DPP4 inhibition is associated with reduced inflammation. In this submission, we explore the potential use of DPP4 inhibitors as therapeutic agents for prediabetic patients in managing the deleterious effects of COVID-19. DPP4 inhibitors (gliptins), such as linagliptin and sitagliptin, have therapeutic effects, which have been shown to extend beyond glycaemic control with no risk of hypoglycaemia. By the nature of their mechanism of action, gliptins are not associated with hypoglycaemia, unlike their anti-glycaemic counterparts, as they mainly target postprandial glycaemia. Moreover, DPP4 inhibitors may represent a safer option for prediabetic individuals in managing prediabetes either as a prophylactic or curative treatment for COVID-19. We envisage that beyond improved glycaemic control, the use of DPP4 inhibitors would also alleviate the cytokine storm, resulting in a reduction in the severity of COVID-19 symptoms and consequently reducing the morbidity and mortality in prediabetic COVID- 19 patients., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

The objective of the review led to the pursuit of adopting dipeptidyl peptidase-4 inhibitors (DPP4i) as a novel pharmacotherapy in diabetes mellitus (DM) and cardiorenal syndrome (CRS). The CRS is defined as the co-existence of myocardial ischemia with renal failure. At present, the commercially available drugs enhance insulin secretion or action. However, most of the drugs are associated with adverse effects, such as weight gain or hypoglycemia. As a result, newer therapies with better safety and efficacy profiles are being explored. The DPP4 protease enzyme is involved in cardiovascular and renal diseases in association with over-expressed cytokines. The novel characteristic of DPP4i is to control the elevated blood glucose levels in response to nutrient ingestion without causing hypoglycemia. Also, DPP4i are indirectly involved in reducing myocardial ischemia by promoting cardioprotective peptides. They protect the glucagon-like peptide 1 (GLP-1) from the deteriorating effect of the DPP4 enzyme. The GLP-1 receptors (GLP-1R) are abundantly expressed in renal and cardiovascular tissue. The overexpression of GLP-1R will confer protection of the heart and kidney during CRS. DPP4i were found to significantly clear plasma glucose by the simultaneously activating natural thrombolytic system and increasing insulin levels. They can be used in the early stages of the disease, including pre-diabetes or obesity combined with impaired incretin response, while the combination of DPP4i with metformin or thiazolidinediones as insulin sensitizers offers an additional improvement in the treatment of DM. With its positive attributes in a host of associated parameters of interest, DPP4i are studied extensively in the present review., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

The increasing number of cases of diabetes mellitus (DM) and related diseases has become a global health concern. In this context, controlling blood glucose levels is critical to prevent and/or slow down the development of diabetes-related complications. Incretins, as gutderived hormones that trigger the post-meal secretion of insulin, are a well-known family of blood glucose modulators. Currently, incretin medications, including glucagon-like peptide-1 receptor agonist (GLP-1RA) and dipeptidyl peptidase-4 (DPP-4) inhibitors, are extensively used to treat patients with type 2 diabetes mellitus (T2D). Several experimental and clinical studies illustrate that these metabolic hormones exert their antidiabetic effects through multiple molecular mechanisms. Accordingly, the current review aims to investigate key mechanisms and signaling pathways, such as the cAMP/PKA, Nrf2, PI3K/Akt, and AMPK pathways, associated with the antidiabetic effects of incretins. It also summarizes the outcomes of a group of clinical trials evaluating the incretins' antidiabetic potential in diabetic patients., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Objectives: In coronavirus disease 2019 (Covid-19), SARS-CoV-2 may use dipeptidyl peptidase 4 (DPP4) as an entry-point in different tissues expressing these receptors. DPP4 inhibitors (DPP4Is), also named gliptins, like sitagliptin, have anti-inflammatory and antioxidant effects, thereby lessen inflammatory and oxidative stress in diabetic Covid-19 patients. Therefore, the present study aimed to illustrate the potential beneficial effect of sitagliptin in managing Covid-19 in non-diabetic patients., Methods: A total number of 89 patients with Covid-19 were recruited from a single center at the time of diagnosis. The recruited patients were assigned according to the standard therapy for Covid-19 and our interventional therapy into two groups; Group A: Covid-19 patients on the standard therapy (n=40) and Group B: Covid-19 patients on the standard therapy plus sitagliptin (n=49). The duration of this interventional study was 28 days according to the guideline in managing patients with Covid-19. Routine laboratory investigations, serological tests, Complete Blood Count (CBC), C-reactive Protein (CRP), D-dimer, lactate dehydrogenase (LDH), and serum ferritin were measured to observed Covid-19 severity and complications. Lung Computed Tomography (CT) and clinical scores were evaluated., Results: The present study illustrated that sitagliptin as an add-on to standard therapy improved clinical outcomes, radiological scores, and inflammatory biomarkers than standard therapy alone in non-diabetic patients with Covid-19 (P<0.01)., Conclusion: Sitagliptin as an add-on to standard therapy in managing non-diabetic Covid-19 patients may have a robust beneficial effect by modulating inflammatory cytokines with subsequent good clinical outcomes., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: Diabetes affects millions of people worldwide, with predicted numbers of about 700 million adults affected by 2045. Among the several anti-diabetic drug therapies available in the market, Dipeptidyl Peptidase-4 (DPP-4) inhibitors have emerged as a promising therapeutic approach with scope for exploration in the segment of peptidomimetics., Objective: Series of proline-containing peptidomimetic compounds were designed and investigated for their drug-likeness through Lipinski's rule of five, lead-likeness through the rule of three, predictive pharmacokinetic studies (absorption, distribution, metabolism, and excretion), and toxicity properties through in-silico approaches. The designed compounds were evaluated for their interactions with binding sites of the enzyme DPP-4 using an extra precision docking approach., Methods: Proline-containing peptidomimetic compounds were designed rationally. Drug-likeness and lead-likeness properties were calculated using Schrödinger Maestro v11.2 software. ADME and toxicity properties were predicted using PreADMET version 2.0. Docking study was performed using Schrödinger Maestro v11.2 software, and ligands for the study were designed using MarvinSketch software., Results: 5(S)-methyl-L-proline containing 17 ligands were designed. All of them were found to obey Lipinski's rule of five. Compounds were found to have good ADME profile and low toxicity predictions., Conclusion: Four compounds were found to have good interactions with DPP-4 binding sites and hence created the scope to develop DPP-4 inhibitors containing 5(S)-methyl-L-proline moiety., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

The fast spread of coronavirus 2019 (COVID-19) calls for immediate action to counter the associated significant loss of human life and deep economic impact. Certain patient populations like those with obesity and diabetes are at higher risk for acquiring severe COVID-19 disease and have a higher risk of COVID-19 associated mortality. In the absence of an effective and safe vaccine, the only immediate promising approach is to repurpose an existing approved drug. Several drugs have been proposed and tested as adjunctive therapy for COVID-19. Among these drugs are the glucagon-like peptide-1 (GLP-1) 2 agonists and the dipeptidylpeptidase-4 (DPP-4) inhibitors. Beyond their glucose-lowering effects, these drugs have several pleiotropic protective properties, which include cardioprotective effects, anti-inflammatory and immunomodulatory activities, antifibrotic effects, antithrombotic effects, and vascular endothelial protective properties. This narrative review discusses these protective properties and addresses their scientific plausibility for their potential use as adjunctive therapy for COVID-19 disease., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Diabetic neuropathy is referred to as a subsequential and debilitating complication belonging to type 1 and type 2 diabetes mellitus. It is a heterogeneous group of disorders with a particularly complex pathophysiology and also includes multiple forms, ranging from normal discomfort to death. The evaluation of diabetic neuropathy is associated with hyperglycemic responses, resulting in an alteration in various metabolic pathways, including protein kinase C pathway, polyol pathway and hexosamine pathway in Schwann and glial cells of neurons. The essential source of neuronal destruction is analogous to these respective metabolic pathways, thus identified as potential therapeutic targets. These pathways regulating therapeutic medications may be used for diabetic neuropathy, however, only target specific drugs could have partial therapeutic activity. Various antidiabetic medications have been approved and marketed, which possess the therapeutic ability to control hyperglycemia and ameliorate the prevalence of diabetic neuropathy. Among all antidiabetic medications, incretin therapy, including Glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors, are the most favorable medications for the management of diabetes mellitus and associated peripheral neuropathic complications. Besides enhancing glucose-evoked insulin release from pancreatic β-cells, these therapeutic agents also play a vital role to facilitate neurite outgrowth and nerve conduction velocity in dorsal root ganglion. Furthermore, incretin therapy also activates cAMP and ERK signalling pathways, resulting in nerve regeneration and repairing. These effects are evidently supported by a series of preclinical data and investigations associated with these medications. However, the literature lacks adequate clinical trial outcomes related to these novel antidiabetic medications. The manuscript emphasizes the pathogenesis, current pharmacological approaches and vivid description of preclinical and clinical data for the effective management of diabetic neuropathy., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: Diabetes, a metabolic disease, occurs due to a decreased or no effect of insulin on the blood glucose level. The current oral medications stimulate insulin release, increase glucose absorption and its utilization, and decrease hepatic glucose output. Two major incretin hormones like Glucose-dependent insulinotropic polypeptide (GIP) and glucagonlike peptide - 1 (GLP-1) stimulate insulin release after a meal, but their action is inhibited by enzyme dipeptidyl peptidase- IV., Objective: The activity of endogenous GLP-1 and GIP prolongs and extends with DPP IV inhibitors, which are responsible for the stimulation of insulin secretion and regulation of blood glucose level. DPP IV inhibitors have shown effectiveness and endurability with a neutral effect on weight as well as less chances of hypoglycemia in the management of type 2 diabetes. These journeys started from Sitagliptin (marketed in 2006) to Evogliptin (marketed in 2015, Korea)., Conclusion: Treatment of type 2 diabetes includes lifestyle changes, oral medications, and insulin. Newer and superior therapies are needed more than currently prescribed drugs. Various heterocyclic derivatives have been tried, but due to masking of DASH proteins, CYP enzymes, and hERG channel, they showed side effects. Based on these, the study has been focused on the development of safe, influential, selective, and long-lasting inhibitors of DPP IV., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Worldwide, diabetes ranks among the ten leading causes of mortality. Prevalence of diabetes is growing rapidly in low and middle income countries. It is a progressive disease leading to serious co-morbidities, which results in increased cost of treatment and over-all health system of the country. Pathophysiological alterations in Type 2 Diabetes (T2D) progressed from a simple disturbance in the functioning of the pancreas to triumvirate to ominous octet to egregious eleven to dirty dozen model. Due to complex interplay of multiple hormones in T2D, there may be multifaceted approach in its management. The 'long-term secondary complications' in uncontrolled diabetes may affect almost every organ of the body, and finally may lead to multi-organ dysfunction. Available therapies are inconsistent in maintaining long term glycemic control and their long term use may be associated with adverse effects. There is need for newer drugs, not only for glycemic control but also for prevention or mitigation of secondary microvascular and macrovascular complications. Increased knowledge of the pathophysiology of diabetes has contributed to the development of novel treatments. Several new agents like Glucagon Like Peptide - 1 (GLP-1) agonists, Dipeptidyl Peptidase IV (DPP-4) inhibitors, amylin analogues, Sodium-Glucose transport -2 (SGLT- 2) inhibitors and dual Peroxisome Proliferator-Activated Receptor (PPAR) agonists are available or will be available soon, thus extending the range of therapy for T2D, thereby preventing its long term complications. The article discusses the pathophysiology of diabetes along with its comorbidities, with a focus on existing and novel upcoming antidiabetic drugs which are under investigation. It also dives deep to deliberate upon the novel therapies that are in various stages of development. Adding new options with new mechanisms of action to the treatment armamentarium of diabetes may eventually help improve outcomes and reduce its economic burden., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Introduction: Hepatic steatosis is a frequent condition that afflicts, especially, obese and insulin-resistant patients. Diagnosis is usually made through imaging tests. Despite the high prevalence and risk of complications, there is no specific treatment approved, though a vast number of medications have been tested., Objective: This study aimed to determine the efficacy of dipeptidyl peptidase IV inhibitors (i DPP- IV) in the treatment of NAFLD., Methods: We searched the electronic databases of the Cochrane Library, MEDLINE, EMBASE, and LILACS, as well as reference lists of the included studies and grey literature; 9 studies were selected for inclusion., Results: 7 studies were used for metanalysis for 3 outcomes. i DPP-IV showed an ALT-reducing power of MD -10.83 (95% CI 35.23 to 13.57) at 3 months and MD -9.27 (95% CI 10.92 to -7.62) at 6 months of intervention, as well as a reduction of hepatic steatosis via MRI of SMD 0.10 (95% CI 0.31 to 0.50); the overall incidence of adverse events was very low. The studies were considered of low and very low quality by the GRADE evaluation., Conclusion: Because of the overall poor quality of the studies and heterogeneity of the population analyzed, i DPP-IV did not show efficacy on inflammatory markers or fibrosis in patients with NAFLD., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

The cardiovascular complications of Type 2 Diabetes Mellitus (T2DM) including myocardial infarction, heart failure, peripheral vascular disease and, stroke and retinopathy, nephropathy and neuropathy are microvascular complications. While the newer therapies like glitazones or even Dipeptidyl- peptidase-IV (DPP-IV) inhibitors increase the risk of therapy, the Glucagon Like Peptide-1 Receptor Agonists (GLP-1RAs), were reported as suitable alternates. The GLP-1RAs reduce Major Adverse Cardiovascular Events (MACE), have anti-atherogenic potential, and possess pleiotropic activity. The GLP-1RAs were found to improve neuroprotection, enhance neuronal growth, reduce the incidence of stroke, and improve central insulin resistance. The GLP-1RAs are beneficial in improving the glycemic profile, preventing macroalbuminuria and reducing the decline in eGFR and enhancing renal protection. The renal benefits of add-on therapy of GLP-1RAs with SGLT-2 inhibitors have composite renal outcomes such as suppression of inflammatory pathways, improvement in natriuresis, diuresis, found to be nephroprotective. Improvement in glycemic control with a reduction in body weight and intraglomerular pressure and prevention of tubular injury makes the GLP-1RAs as suitable add-on therapies in improving cardiorenal outcomes. Obesity, an important contributor to insulin resistance and a reduction in weight, is an essential therapeutic option in addressing diabetic-obesity. It also reduces the damage to blood-retinal-barrier, thus beneficial in halting the development of diabetic retinopathy. In diabetic complications, glycemic control, addressing insulin resistance through weight loss, controlling atherosclerosis through anti-inflammatory effects and cardio-renal-neuro protection, makes GLP-1RAs a suitable therapeutic strategy on long-term treatment of T2DM. This review discusses the role of GLP-1RAs in diabetes, the dosage, mono or combination therapy with other antidiabetics in long-term treatment and its effect in uncontrolled diabetes., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Introduction: The enzyme called dipeptidyl peptidase IV (DPP-IV) is related to the glycemic control associated with the stimulation of the pancreas to produce insulin. So, its inhibition is a good strategy for the treatment of type 2 diabetes mellitus., Methods: In this study, we have employed molecular modeling strategies such as CoMFA, molecular docking, molecular dynamics, and binding free energy calculations of a set of DPP-IV inhibitors in order to understand the main characteristics related to the biological activity of these ligands against the enzyme., Results: The models obtained from CoMFA presented significant values of internal (0.768) and external (0.988) validations. Important interactions with some residues, such as Glu205, Tyr666, Arg125, Ser630, Phe357 and Tyr662, were also identified. In addition, calculations of the electronic properties allowed relating the LUMO and HOMO energies with the biological activity of the compounds studied. The results obtained from the molecular dynamics simulations and the SIE calculations (ΔG) indicated that the inhibitor 40 increases the stability of the DPP-IV target., Conclusions: Therefore, from this study, it is possible to propose molecular modifications of these DPP-IV inhibitors in order to improve their potential to treat type 2 diabetes., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: Kidney transplant recipients may develop post-transplant diabetes mellitus (PTDM). Dipeptidyl peptidase 4(DPP-4) inhibitors are evolving agents in the management of patients with diabetes mellitus., Aim: To evaluate the efficacy and safety of DPP-4 inhibitors in the management of post-transplant diabetes mellitus (PTDM) in renal transplant recipients., Methods: We performed a systematic search of the electronic databases using keys words and Mesh terms. Data were extracted and reviewed using structured proforma. A comprehensive review of the eligible studies was performed independently by each of two reviewers; conflicts were resolved by the third reviewer. The primary efficacy endpoint was the difference in glycosylated hemoglobin (HbA1c) comparing any of the DPP-4 inhibitors to either placebo or other hypoglycaemic agent. The primary safety endpoints were the worsening of graft functions and change in Tacrolimus trough level. We performed the Random effect model using standardised mean difference., Results: We identified seven studies that were eligible for the systematic review; only one study compared Sitagliptin to insulin Glargine. One study involved head to head comparison of three DPP-4 inhibitors. The other five studies were pooled in the meta-analysis. DPP-4 inhibitors had a favourable glycemic effect as measured by HbA1c when compared to either placebo or oral anti-hyperglycemic medications (standardised mean difference in HbA1c = -0.993, 95% CI= -1.303 to -0.683, P=0.001). DPP-4 inhibitors use did not result in significant change in eGFR ((standardised mean difference = 0.147, 95% CI= -0.139 - 0.433, p=0.312).) nor Tacrolimus level (standardised Mean Difference= 0.152, 95% CI= -0.172 to 0.477, P=0.354)., Conclusion: Current evidence supports the short term efficacy and safety of DDP-4 inhibitor agents in the management of post transplantation diabetes mellitus (PTDM) in kidney transplant recipients. However, more RCTs are required to investigate the long-term safety and efficacy of these agents in kidney transplant recipients., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: Cardiovascular complications account for the majority of deaths caused by diabetes mellitus. Platelet hyperactivity has been shown to increase the risk of thrombotic events and is a therapeutic target for their prevention in diabetes. Modulation of platelet function by diabetes agents in addition to their hypoglycemic effects would contribute to cardiovascular protection. Newly introduced antidiabetic drugs of sodium-glucose cotransporter 2 inhibitors (SGLT2i), glucagon like peptide-1 receptor agonists (GLP-1RA) and dipeptidyl peptidase-4 inhibitors may have anti-platelet effects, and in the case of SGLT2i and GLP-1RA may contribute to their proven cardiovascular benefit that has been shown clinically., Objective: Here, we reviewed the potential effects of these agents on platelet function in diabetes., Results and Conclusion: GLP-1RA and DPP-4i drugs have antiplatelet properties beyond their primary hypoglycemic effects. Whilst we have little direct evidence for the antiplatelet effects of SGLT2 inhibitors, some studies have shown that these agents may inhibit platelet aggregation and reduce the risk of thrombotic events in diabetes., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

This article provides comprehensive and collective facts about teneligliptin. Teneligliptin is a dipeptide peptidase-4 (DPP-4) inhibitor that belongs to the third generation, used in the management of type 2 diabetes. It inhibits human DPP-4 enzyme activity. This drug falls under class 3; it interacts with S1, S2, and S2E extensive sub-sites. Teneligliptin and its metabolites are mainly determined in the human plasma matrix by hyphenated chromatographic methods. These developed methods could be foreseen for their clinical applications. Moreover, the stress degradation studies of Teneligliptin under different stress conditions provide an insight into degradation pathways and help in the elucidation of the structure of the degradation products by liquid mass spectroscopy. These methods are also used for routine quality control analysis of teneligliptin in pharmaceutical dosage forms., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: We have found that anagliptin, a dipeptidyl peptidase-4 inhibitor (DPP-4) significantly ameliorates arterial stiffness in Type 2 Diabetes Mellitus (T2DM) patients compared with an equivalent hypoglycaemic agent, glimepiride. However, it remains unclear whether switching DPP-4 inhibitors to tofogliflozin, a selective inhibitor of Sodium-Glucose Cotransporter 2 (SGLT2) improves arterial stiffness in T2DM patients., Methods: Nineteen T2DM patients who had received DPP-4 inhibitors for at least 1 year were enrolled in this study. Clinical parameters and arterial stiffness evaluated by cardio-ankle vascular index (CAVI) were measured at baseline and after 6-months treatment with tofogliflozin., Results: At 6 months after switching to tofogliflozin, CAVI, waist circumference, body weight, body mass index, subcutaneous and visceral fat volume, white blood cell number, fasting plasma insulin, uric acid, aspartate transaminase (AST), γ-glutamyl transferase (GTP), and advanced glycation end products (AGEs) were significantly reduced, while red blood cell number, haemoglobin, and HbA1c values were increased. When stratified by median values of change in CAVI after switching to tofogliflozin (ΔCAVI), baseline serum levels of AGEs were significantly higher in the low ΔCAVI group (high responder) than in the high one (low responder). ΔAST and ΔGTP were positively correlated with ΔCAVI., Conclusion: The present study suggests that switching DPP-4 inhibitors to tofogliflozin ameliorates arterial stiffness in T2DM patients partly via improvement of liver function. Baseline serum levels of AGEs may identify patients who improve arterial stiffness more after treatment with tofogliflozin., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Diabetes mellitus is an emerging predator and affecting around 422 million adults worldwide. Higher levels of circulating insulin and increased pressure on the pancreas to produce insulin have been inferred as possible etiology for diabetes leading to a higher risk of pancreatic cancer. Out of several drug targets in hypoglycemic discovery, Dipeptidyl peptidase-IV (DPP-IV) has been considered an emerging target. It is a protease enzyme which inactivates incretin hormones i.e., Glucagonlike peptide 1 (GLP-1) and glucose-dependent insulin tropic polypeptide (GIP). Inhibition of DPP-4 results in the longer action of GLP-1 and GIP, therefore, DPP-4 inhibitors play an important role in maintaining glucose homeostasis. In comparison to early oral hypoglycemic, DPP-IV inhibitors are well tolerated and provide a better glycemic control over a longer period. These enzymes are expressed in a dimeric form on the surface of different cells such as prostate, liver and small intestinal epithelium cells. Disruption of the local signaling environment is an emerging factor in cancer development. Till date, not even a single DPP-IV inhibitor as anticancer has been developed. This review focuses on various features of the enzyme and their suitable inhibitors for target disease., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Latent Autoimmune Diabetes in Adults (LADA), although formally classified as Type 1 Diabetes (T1D), very often (at least in Western countries) appear clinically with Type 2 Diabetes (T2D)-like features as overweight and insulin resistance. LADA patients do not need exogenous insulin at the time they are diagnosed with diabetes, but a large percentage will within a few years develop need for such treatment. The decline in beta cell function progresses much faster in LADA than in T2D, presumably because of the ongoing autoimmune assault in LADA, and therefore necessitates insulin therapy much earlier in LADA than in T2D. Despite high prevalence of LADA (about 10% of the total diabetic population in many countries), the treatment of LADA patients is far less elucidated than is the case for T1D and T2D. Finding a treatment strategy for LADA from the time of diagnosis, that can reduce the decline of beta cell function, ensure adequate metabolic control and thereby reduce the risk of diabetic complications is thus an important clinical challenge. Conclusions from the randomized treatment studies so far do not indicate an optimal treatment strategy in LADA. This review aims to give an overview of current practices for the medical treatment of LADA as well as an update on results from recent studies on the treatment of the disease., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: Recent findings indicate that incretin hormones and incretin-based therapies may affect the metabolism of lipoproteins, although the corresponding mechanisms are not clearly defined., Objective: To summarize the available data on the mechanisms linking incretins with the characteristics of serum lipoproteins and discuss the clinical implications of these relationships., Methods: PubMed was searched using the terms "incretins", "GLP-1", "GIP" and "lipids", "dyslipidemia", "triglycerides", "apolipoprotein B48". All articles published in the English language until June 2016 were assessed and the relevant information is presented here., Results: GLP-1, and therapies that increase its activity, exert a beneficial effect on lipoprotein metabolism that is translated in a reduction in the fasting and postprandial concentration of triglycerides and a small improvement in the concentration and function of HDLs. In addition, a shift towards larger, less atherogenic particles usually follows the administration of GLP-1 receptor agonists. The mechanisms that underlie these changes involve a direct effect of GLP- 1 on the hepatic and intestinal production of triglyceride-rich lipoproteins, the GLP-1 induced increase in the production and function of insulin, the activation of specific areas of central nervous system as well as the increase in the peripheral utilization of triglycerides for energy production. On the other hand, GLP-2 increases the absorption of dietary fat and the production of triglyceride-rich lipoproteins while the role of GIP on lipid metabolism remains indeterminate., Conclusion: GLP-1 and incretin-based therapies favorably affect lipid metabolism. These effects may contribute to the beneficial effects of incretin-based therapies on atherosclerosis and fatty liver disease., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

It is known that Cardiovascular (CV) disease is the leading cause of morbidity and mortality in individuals with type 2 diabetes. Over the last years, one of the most discussed topics is the CV safety of anti-diabetic medications. Regarding CV safety of older antidiabetic agents the data are less clear and conclusions about their CV safety are mostly based on randomized controlled trials designed to assess their glucose lowering efficacy. In this review, we summarize the current knowledge about the CV safety of older and newer antidiabetic medications. According to the published literature metformin is the first line agent for the treatment of type 2 diabetes and seems to have cardio-protective effects. The choice of the second line agent when metformin monotherapy fails to achieve HbA1c targets is less clear. In the light of the findings of the EMPA-REG OUTCOME trial and the recently published LEADER and SUSTAIN 6 trials, empagliflozin, liraglutide and semaglutide seem reasonable options as second line agents for patients with CV disease. Sulfonylureas on the other hand, with the exception of gliclazide, should be avoided in those patients, although CV safety trials are still lacking. In individuals without CV disease any of the other classes of anti-diabetic medication can be selected on a patient-centered approach. Saxagliptin, alogliptin, sitagliptin and lixisenatide have been evaluated in CV safety trials and have neutral effects on CV outcomes, while pioglitazone may have some CV benefits. Saxagliptin and alogliptin, however, should be avoided in patients with heart failure, while pioglitazone is contraindicated in this population., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Type 2 diabetic patients are known to have a tendency to develop cardiovascular (CV) disease (CVD), and related unfavourable outcomes such as heart failure, myocardial infarction (MI), cerebrovascular events (e.g. stroke), and related mortality. Long- term clinical trials have revealed contradictory findings regarding the relationship between glycemic control and CV benefits due to variations in the key characteristics of the study population. During the last decade, number of pharmacological agents used for glucose- lowering in the treatment of type 2 diabetes mellitus (T2DM) has increased owing to the introduction of dipeptidyl peptidase- IV (DPP- IV) inhibitors, glucagon- like peptide- 1 (GLP- 1) receptor agonists, and sodium-glucose co-transporter 2 (SGLT- 2) inhibitors. This review aims to focus on the mechanisms of action of these drugs in the cardiovascular system and the trials evaluating their impact on CVD. Furthermore, trials in the last decade evaluating the impact of traditional glucose- lowering drugs on CVD are included. For this purpose, we searched PubMed for articles in English using the search terms "type 2 diabetes mellitus, glucose- lowering drugs, antidiabetic medications, cardiovascular, cardiovascular disease, cardiovascular system" between inception to September 2016. We also searched separately for each medication in addition to the keyword "cardiovascular disease" on PubMed. To identify further articles, we hand searched related citations in review articles and commentaries., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Background: Inhibition of dipeptidyl peptidase-4 (DPP-4) has been proposed as a therapeutic target for type 2 diabetes (T2DM). Arterial stiffness, a predictor of future cardiovascular events and all-cause mortality, is augmented in these patients. However, effects of DPP-4 inhibitors on arterial stiffness remain unknown. In this study, we compared effects of anagliptin, an inhibitor of DPP-4 on arterial stiffness evaluated by cardio-ankle vascular index (CAVI) with those of an equipotent glucose-lowering agent, glimepiride in patients with T2DM., Methods: The study involved 50 consecutive outpatients (33 males and 17 females; mean age of 72.5±9.5 years) who visited our hospitals for a risk-screening test or treatment for T2DM. They underwent complete history and physical examination, and determination of blood chemistry and anthropometric variables, and then were randomized to receive either anagliptin (n=26) or glimepiride (n=24) for 6 months., Results: After 6-months treatment, fasting plasma glucose and HbA1c values were comparably reduced in both groups. Anagliptin, but not glimepiride treatment significantly decreased low-density lipoprotein cholesterol, malondialdehyde-modified LDL, remnant-like particle (RLP) cholesterol, CAVI, alanine transaminase (ALT), γ-glutamyl transferase and visceral fat volume. In multiple regression analysis, absolute changes from baseline of RLP cholesterol and ALT after anagliptin treatment for 6 months (ΔRLP cholesterol and ΔALT) were independently correlated with ΔCAVI (R2=0.445)., Conclusion: The present study suggests that anagliptin may exert a beneficial effect on arterial stiffness in patients with T2DM, which is independent of its blood glucose-lowering property. Anagliptin may ameliorate arterial stiffness partly via reduction of RLP cholesterol and improvement of liver function.

Background: We conducted a comparison between the dipeptidyl-peptidase-4(DPP-4) inhibitor sitagliptin versus NPH insulin as an add-on therapies in patients with type 2 diabetes mellitus (T2D) failing oral medications. The objective was to ascertain the better indication in long-duration diabetes., Methods: thirty-five T2D patients inadequately controlled with metformin plus glyburide were randomized to receive sitagliptin (n=18) or bedtime NPH insulin (n=17) for 12 months. HbA1c levels and a metabolic and hormonal profile at fasting and post-meal (every 30 minutes for 4 hours) were evaluated before and after 6 months (short-term) and 12 months (long-term) after adding sitagliptin or bedtime NPH insulin to their drug regime., Results: Sitagliptin and NPH insulin decreased HbA1c levels equally after 6 months (p<0.001) with no further improvement after 12 months: sitagliptin (8.1±0.7% vs. 7.3±0.8% vs. 7.4±1.9%) and insulin (8.1±0.6% vs. 7.3±0.7% vs. 7.2±1.0%). Fasting glucose, fasting and postprandial triglyceride and C-peptide levels were also reduced by NPH insulin whereas postprandial insulin was decreased by sitagliptin. Body weight and postchallenge free fatty acid levels increased with insulin treatment. The transitory suppression (at 6 months) of postprandial proinsulin levels with both therapies, and of glucagon with sitagliptin, was followed by values similar or worse to those at pre-treatment., Conclusion: The use of either NPH insulin or a DPP-4 inhibitor as add-on treatments improves glucose control in patients with T2D failing on metformin plus glyburide therapy. The results were not attributed to a permanent improvement in alpha or beta cell function in patients with long-duration diabetes., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Background: Parkinson's disease is a chronic neurodegenerative disorder characterized by a progressive loss of dopaminergic neurons. The pathophysiological mechanisms underlying Parkinson's are still unknown. Mitochondrial dysfunction, abnormal protein aggregation, increased neuroinflammation and impairment of brain glucose metabolism are shared processes among insulinresistance, diabetes and neurodegeneration and have been suggested as key mechanisms in development of Parkinson's and cognitive impairment., Objective: To review experimental and clinical evidence of underlying Parkinson's pathophysiology in common with diabetes and cognitive impairment. Anti-diabetic agents and recent patents for insulin-resistance that might be repositioned in the treatment of Parkinson's also have been included in this review., Method: A narrative review using MEDLINE database., Results: Common antidiabetic treatments such as DPP4 inhibitors, GLP-1 agonists and metformin have shown promise in the treatment of Parkinson's disease and cognitive impairment in animals and humans. Study of the pathophysiology of neurodegeneration common between diabetes and Parkinson's disease has given rise to new treatment possibilities. Patents published in the last 5 years could be used in novel approaches to Parkinson's treatment by targeting specific pathophysiology proteins, such as Nurr1, PINK1 and NrF2, while patents to improve penetration of the blood brain barrier could allow improved efficacy of existing treatments., Conclusion: Further studies using GLP-1 agonists and DPP-4 inhibitors to treat PD are warranted as they have shown promise.

Diseases started even before the existence of human beings. Therefore, when the civilization began, the biggest threats for human were diseases. Man has made several sincere attempts for the search of new drugs in order to cure and control different diseases. Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder that accounts for about 85-95% of all diagnosed cases of diabetes. It is characterized by abnormalities in glucose homeostasis in many organs, and is associated with considerable morbidity and mortality. Extensive research has been carried out using rational drug design to identify and optimize new leads for molecular targets of T2DM, which include Heterocyclic compounds, metal complexes, H3 receptor antagonists, glucagon receptor antagonists and human incretin-degrading enzyme dipeptidyl peptidase IV inhibitors.

Non-alcoholic fatty liver disease (NAFLD) is the commonest chronic liver disease and is more prevalent in patients with type 2 diabetes mellitus (T2DM). Incretin-based antidiabetic agents (glucagonlike peptide-1 (GLP-1) receptor agonists and dipeptidyl peptidase-4 (DPP-4) inhibitors) are used in the treatment of T2DM but it is unclear whether they may also play a role in the management of NAFLD. We systematically reviewed the PubMed and Scopus database up to October 2014 and also hand-searched the references of the retrieved articles for studies evaluating the effects of these agents on NAFLD. In animal studies, both GLP-1 receptor agonists and DPP-4 inhibitors reduced transaminase activity and steatosis but their effects on liver inflammation were inconsistent and fibrosis was not assessed. In clinical studies, both agents consistently reduced transaminase activity and steatosis as assessed non-invasively. There are very limited data on the effects of incretin-based treatments on liver histology. In conclusion, GLP-1 receptor agonists and DPP-4 inhibitors appear to hold promise in patients with NAFLD but larger controlled studies with histological and clinical endpoints are needed to evaluate their effects in this population.

Prospective epidemiological studies suggest that type 2 diabetes is a risk factor for neurodegenerative pathologies such as Alzheimer disease, vascular dementia, and Parkinson disease. Drugs that act as incretin receptor agonists or inhibit the proteolytic degradation of incretins (dipeptidyl peptidase 4 inhibitors) have been approved since 2005 for use in diabetes treatment. Dipeptidyl peptidase 4 (DPP4) cleaves N-terminal dipeptides from polypeptides when the second residue is proline, hydroxyproline, dehydroproline or alanine. The inhibition of DPP4 hydrolytic activities extends the halflife of these peptides by preventing their degradation. Several peptides have been identified as DPP4 substrates, including neuropeptides, chemokines, and the incretin hormones; hence the pleomorphic effects of DPP4 inhibition. Recently, the neuroprotective properties of these drugs have been evaluated in cell cultures and animal models, not yet in human trials. Although mechanisms distinct from glycaemic control alone have been claimed to account for protection against neuronal degeneration, the precise cellular mechanism by which DPP4 inhibitors exert their neuroprotective effects remain unknown. The present review is focused on the candidate pathways that could be involved in mediating DPP4 inhibitors-mediated protection against neuronal degeneration.

Chronic hyperglycemia and its associated metabolic products are key factors responsible for the development and progression of diabetic chronic kidney disease (CKD). Endocrinologists are tasked with detection and management of early CKD before patients need referral to a nephrologist for advanced CKD or dialysis evaluation. Primary care physicians are increasingly becoming aware of the importance of managing hyperglycemia to prevent or delay progression of CKD. Glycemic control is an integral part of preventing or slowing the advancement of CKD in patients with diabetes; however, not all glucose-lowering agents are suitable for this patient population. The availability of the latest information on treatment options may enable physicians to thwart advancement of serious renal complication in patients suffering from diabetes. This review presents clinical data that shed light on the risk/benefit profiles of three relatively new antidiabetes drug classes, the dipeptidyl peptidase-4 inhibitors, glucagon-like peptide-1 analogs, and sodium glucose co-transporter 2 inhibitors, particularly for patients with diabetic CKD, and summarizes the effects of these therapies on renal outcomes and glycemic control for endocrinologists and primary care physicians. Current recommendations for screening and diagnosis of CKD in patients with diabetes are also discussed.

Current treatment modalities for critical limb ischemia (CLI) are of limited benefit; therefore, advances in therapeutic vasculogenesis may open an important new avenue for the treatment of CLI. This study examines the therapeutic potential of the DPP-4 inhibitor MK-0626 as a regulator of vasculogenesis in vivo. MK-0626 was administered daily to C57CL/B6 mice and eGFP-labeled bone marrow-transplanted ICR mice that had undergone hind limb ischemia surgery. Laser Doppler imaging and flow cytometry were used to evaluate the degree of neo-vasculogenesis and the number of circulating endothelial progenitor cells (EPCs), respectively. Cell surface markers of EPCs and the level of endothelial nitric oxide synthase (eNOS) were studied in the vessels. Mice that received MK-0626 had an elevated level of glucagon- like peptide-1 (GLP-1) and a decreased level of dipeptidyl peptidase-4 (DPP-4) in their plasma, in addition to an ischemia-induced increase in the level of stromal cell-derived factor-1 (SDF-1). In C57CL/B6 mice, blood flow in the ischemic limb was significantly improved by treatment with MK-0626. The number of circulating EPCs and both the synthesis and phosphorylation of eNOS were also increased in ischemic thigh muscle after MK-0626 treatment. In contrast, similar effects of MK-0626 were not observed in B6.129P2-Nos3(tm1Unc)/J mice (an eNOS knockout mouse). Additionally, MK-0626 treatment promoted the mobilization and homing of EPCs to ischemic tissue in eGFP transgenic mouse bone marrow-transplanted ICR mice. We conclude that both the number of circulating EPCs and neo-vasculogenesis are increased in response to DPP-4 inhibitor treatment and that this occurs via an eNOS-dependent mechanism. The results highlight the therapeutic vasculogenesis potential of the DPP-4 inhibitor MK-0626 using a hind limb ischemia mouse model.

Type 2 diabetes mellitus (T2DM) is associated with risk for chronic kidney disease (CKD), which is associated with a decrease in renal myogenic tone - part of renal autoregulatory mechanisms. Novel class of drugs used for the treatment of T2DM, dipeptidyl peptidase-4 (DPP-4) inhibitors, have protective effects on the cardiovascular system. A Zucker Diabetic Fatty (ZDF) rat is an animal model of T2DM that displays progressive nephropathy in which inflammation leads to initiation of renal fibrosis and CKD. We hypothesized that CKD in the ZDF rat is related to decrease in myogenic constriction (MC) of intrarenal arteries and that treatment with the DPP-4 inhibitor, vildagliptin, prevents such changes. Renal arteries isolated from 25 weeks old lean, ZDF and ZDF treated with vildagliptin (n=7 in each group) were transferred to an arteriograph to assess agonist and pressure induced contractile responses. Furthermore, blood glucose, proteinuria, focal glomerulosclerosis (FGS) and p22phox mRNA expression of renal tissue were measured. Compared to lean controls, ZDF had significantly increased plasma glucose and cholesterol levels, focal glomerulosclerosis and interstitial α-SMA expression, and urinary protein excretion. ZDF rats also had impaired MC of renal arteries and increased renal p22phox expression. Vildagliptin did not affect plasma glucose levels or proteinuria, but effectively decreased glomerulosclerosis and restored MC and p22phox expression to the levels found in lean rats. Based on these data, it can be suggested that vildagliptin treatment protects diabetic rats from the loss of renal vascular reactivity and the development of glomerulosclerosis perhaps secondary to a reduction in oxidative stress.

Type 2 diabetes mellitus (T2DM) is characterized by a progressive failure of pancreatic β-cell function (BCF) with insulin resistance. Once insulin over-secretion can no longer compensate for the degree of insulin resistance, hyperglycemia becomes clinically significant and deterioration of residual β-cell reserve accelerates. This pathophysiology has important therapeutic implications. Ideally, therapy should address the underlying pathology and should be started early along the spectrum of decreasing glucose tolerance in order to prevent or slow β-cell failure and reverse insulin resistance. The development of an optimal treatment strategy for each patient requires accurate diagnostic tools for evaluating the underlying state of glucose tolerance. This review focuses on the most widely used methods for measuring BCF within the context of insulin resistance and includes examples of their use in prediabetes and T2DM, with an emphasis on the most recent therapeutic options (dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists). Methods of BCF measurement include the homeostasis model assessment (HOMA); oral glucose tolerance tests, intravenous glucose tolerance tests (IVGTT), and meal tolerance tests; and the hyperglycemic clamp procedure. To provide a meaningful evaluation of BCF, it is necessary to interpret all observations within the context of insulin resistance. Therefore, this review also discusses methods utilized to quantitate insulin-dependent glucose metabolism, such as the IVGTT and the euglycemic-hyperinsulinemic clamp procedures. In addition, an example is presented of a mathematical modeling approach that can use data from BCF measurements to develop a better understanding of BCF behavior and the overall status of glucose tolerance.

Inhibition of DPP-IV enzyme has taken centre stage as a validated drug target for type 2 diabetes therapy and as a result of research efforts done towards developing effective DPP-IV inhibitors, the first clinical candidate of this class came in focus in 1998. Thus, from 1998 to 2013, these 16-years have witnessed heightened research activities in the discovery and development of clinically relevant inhibitors of DPP-IV as antidiabetic agents. The effective DPP-IV inhibitors have played a key role in this endeavour and as result there are eight approved gliptins in the clinical usage while others are in different stages of clinical trials. A wide variety of DPP-IV inhibitors were synthesized and evaluated; and were classified into several categories based on their core structural features. In this article, classification of all the clinically relevant DPP-IV inhibitors based on selectivity, clinical efficacy and safety profiles is reviewed in terms of generations. This review also encompasses clinical phase wise discussion, developmental progress, chemistry and binding modes of all clinical DPP-IV inhibitors. In addition, major challenges facing the future design and development of safe clinical DPP-IV inhibitor are also briefly mentioned.

Incretin peptides are a group of gastrointestinal hormones that play a prominent role in the regulation of glucose metabolism. Incretin-based therapies (IBTs) have recently emerged as an important treatment option for patients with type 2 diabetes mellitus (T2DM). These pharmaceutical agents may be specially well suited for patients who are overweight or obese with primarily post-meal glucose peaks, and in whom traditional first-line oral agents have failed to maintain adequate glycemic control. There are 2 classes of IBTs: the dipeptidyl peptidase-4 (DPP-4) inhibitors and the glucagon-like peptide 1 (GLP-1) receptor agonists. The ultimate effect of both types of agents is to augment GLP-1 signaling, which results in enhanced glucose-dependent insulin secretion, inhibition of glucagon secretion and decreased appetite. This leads to improved regulation of glucose homeostasis accompanied by either no increase in body weight (with DPP-4 inhibitors) or a reduction (with GLP-1 receptor agonists). GLP-1 inhibits food intake and the increased GLP-1 response may contribute as a satiety signal. Although data regarding the effect of GLP-1 agonists and DPP-4 inhibitors on levels of peptides involved in the regulation of food intake in T2DM are few, an indirect effect of IBT on weight loss is possible (e.g. Exendin-4 induces adiponectin secretion in vitro). Results from animal models indicate reduction of food intake and body weight by GLP-1 agonists, but follow-up studies are required. A growing amount of evidence suggests that these peptides may also impact the cardiovascular system, including beneficial effects on myocardial cells, lipid profiles and blood pressure as well as reduced markers of systemic inflammation and improved endothelial dysfunction. The potential role of these agents in improving components of the metabolic syndrome and retardation of atherosclerosis needs to be fully elucidated. Although IBTs are currently recommended only for use in the early treatment of T2DM, the 'non-glycemic' actions of these drugs may have far reaching therapeutic implications. It is hoped that future studies will elucidate their potential strengths and weaknesses for use in various metabolic conditions.

Dipeptidyl peptidase-4 inhibitors (DPP-4 inhibitors) are effective and safe oral incretin-based antihyperglycemic drugs. In preclinical studies, DPP-4 inhibitors have demonstrated cardiovascular benefits, independent of glycemic control, in patients with type-2 diabetes mellitus. Since 2005, various DPP-4 inhibitors (sitagliptin, linagliptin and saxagliptin) have been clinically available in the United States. Since 2013, alogliptin is the 4(th) approved DPP-4 inhibitor available on the market. Studies have shown that alogliptinis non-inferior to comparator drugs among newly diagnosed type 2 diabetes mellitus patients. Alogliptin can effectively be used as a single agent or as an add-on drug in combination with other glucose lowering drugs with favorable outcomes on glycemic control and HbA1C levels.

Dipeptidyl peptidases 4 (DPP4) inhibitors are a new class of oral anti-hyperglycemic drugs for the treatment of type 2 diabetes (T2DM). They are also called "incretins" because they act by inhibiting the degradation of endogenous incretin hormones, in particular GLP-1, that mediates their main metabolic effects. DPP4 is an ubiquitous protease that regulates not only glucose and lipid metabolism, but also exhibits several systemic effects at different site levels. DPP4 inhibition improves endothelial function, reduces the pro-oxidative and the pro-inflammatory state, and exerts renal effects. These actions are mediated by different DPP4 ligands, such as cytokines, growth factors, neuotransmitters etc. Clinical and experimental studies have demonstrated that DPP4 inhibitors are efficient in protecting cardiac, renal and vascular systems, through antiatherosclerotic and vasculoprotective mechanisms. For these reasons DDP4 inhibitors are thought to be "cardiovascular protective" as well as anti-diabetic drugs. Clinical trials aimed to demonstrate the efficacy of DPP4 inhibitors in reducing cardiovascular events, independent of their anti-hyperglycemic action, are ongoing. These trials will also give necessary information on their safety.

Type 2 Diabetes Mellitus (T2D) and osteoporosis have been found recently to be tightly correlated. In fact, T2D can result in bone loss through different mechanisms resulting in alteration of bone matrix and inhibition of bone formation. Fracture risk also increases significantly. New antidiabetic agents, dipeptidyl peptidase-4 inhibitors and glucagon like peptide -1 agonists have shown promise in many fields beyond glycemic control. Benefits on the skeletal system are multiple through direct stimulation of osteoblasts, inhibition of advanced glycation end products and inhibition of bone resorption. However, clinical evidence in humans is still not enough to allow definitive conclusions.

Insulin resistance has been associated with the development of type 2 diabetes, obesity, hypertension, dyslipidemia, atherosclerosis, and thus with increased cardiovascular morbidity and mortality. Insulin resistance precedes the onset of type 2 diabetes by many years. Targeting the pathophysiologic defects that characterize the onset of diabetes is more likely to achieve a durable glucose control and to delay disease progression. Incretins are gut-derived peptides that stimulate in a glucose-dependent mechanism insulin secretion and action. Glucose-like peptide 1 (GLP-1) analogues and dipeptidyl peptidase-4 (DPP-4) inhibitors both decrease fasting and postprandial glucose levels. In addition, GLP-1 analogues promote weight loss and exert a favorable effect on several cardiovascular risk factors. Data from human and experimental studies implicate that GLP-1 analogues and to a less extend DPP-4 inhibitors enhance insulin sensitivity. This review summarizes the current knowledge regarding the impact of GLP-1 analogues and DPP-4 inhibitors on insulin resistance.

The increasing epidemic of diabetes mellitus around the globe is increasing the risk of various other chronic diseases i.e. coronary artery diseases, myocardial infarction, hypertension, dyslipidemia and number of other complicated disorders. Diabetes mellitus is clinically characterized by a marked increase in blood glucose levels and is associated with mild hyperlipidemia. Although the prevalence of this health ailment is increasing dramatically, various therapeutic compounds have been developed to treat this disease that is available in the market as synthetic, formulated and combined forms. Recently, various compounds have come through preclinical studies and shown the therapeutic efficacy of using multiple/ specific drug targets. Recent research approaches have been based on receptors targeting, islet cell transplantation, gene expression profiling, glucagon-like peptide-1, dipeptidyl peptidase IV inhibitors, insulin therapy, modulators of peroxisome proliferator-activated receptors (PPAR), glucagon receptor antagonists, insulin analogues, sensitizers and combination therapies. Furthermore various, latest findings claimed to identifying new anti-diabetic regimens with novel mechanism of action are being developed. This review provides an update on the use of approaches to the development of preventive and therapeutic strategies against diabetes and recent patents that could develop into novel therapeutics available to the clinical success for the management of the disease.

Dyslipidemia is a prominent feature of type 2 diabetes and insulin resistance that contributes to increased atherosclerosis and cardiovascular disease (CVD) risks under these conditions. Incretin-based therapies (GLP-1 receptor agonists and DPP-4 inhibitors) have recently been developed and are approved for clinical use for treatment of type 2 diabetes. Besides improved glycemic control, other benefits are being increasingly appreciated, one of which is improved plasma lipid profile. This review aims to summarize the evidence and potential mechanism of such agents in humans in modulating fasting and postprandial lipoprotein metabolism.

Given the demonstrated importance of the incretin effect on the prandial insulin response, augmentation of the incretin effect in people with type 2 diabetes is an important pharmacological approach to glycemic management. In recent years, the use of incretin-based therapies, such as GLP-1 receptor agonists and DPP-4 inhibitors, has increased dramatically due to their demonstrated efficacy, low risk of hypoglycemia when used as monotherapy, and reasonable tolerability. Given their effects on glycemic parameters and the likelihood of aiding in weight loss, GLP-1 receptor agonists provide a unique treatment option for people with type 2 diabetes. Increased clinical experience and study of incretin-based therapies will help answer questions about safety issues that have arisen from post-marketing reports. The potential benefit of incretin-based therapies in the treatment of people with type 2 diabetes and cardiovascular disease is currently an active area of inquiry. While the potential benefits of incretin-based therapies in the arena of cardiovascular risk reduction are promising, results from ongoing outcomes-based studies will help determine the role of these agents in this setting.

Patients with type 2 diabetes mellitus are at high risk for developing cardiovascular diseases. Traditional medicines for type 2 diabetes, such as sulfonylureas, pioglitazone, and insulin have glucose lowering effects; however, they also increase the frequency of hypoglycemia and/or body weight and thus may cancel out the benefits of glucose lowering on the development of atherosclerosis. In contrast, the recently developed glucagon like peptide-1-based therapy using glucagon-like peptide-1 receptor agonists or dipeptidyl peptidase-4 inhibitors has numerous beneficial effects in the management of hyperglycemia with less risk of hypoglycemia and weight gain. Glucagon-like peptide-1-based therapy also lowers blood pressure and blood lipids and thus may prevent progression of atherosclerosis. Furthermore, glucagonlike peptide-1 receptors are abundantly expressed in vascular cells such as endothelial cells, monocyte/macrophages and smooth muscle cells. Recent studies suggest that the anti-inflammatory and vasodilatory properties of glucagon-like peptide-1 signaling on endothelial cells, its anti-inflammatory effect on macrophages and anti-proliferative effects on smooth muscle cells may halt atherosclerosis. Although large clinical trials are required to confirm these beneficial effects, glucagon-like peptide-1-based therapy could provide both glucose lowering and protection against cardiovascular diseases in patients with type 2 diabetes.

The endothelium is critical for multiple processes occurring on both sides of the vascular wall including regulation of blood flow, maintenance of blood fluidity and control of inflammation. Endothelial dysfunction is an early event in the pathogenesis of atherosclerosis and appears to be a critical determinant of cardiovascular events. It is frequently detected in the early stages of type 2 diabetes and even in pre-diabetes conditions. Risk factors for endothelial dysfunction are numerous and include among others fasting and postprandial hyperglycemia and hyperlipidemia, hypertension, obesity, insulin resistance and inflammation. Many of these conditions can be improved by synthetic glucagon like peptide 1 (GLP-1) mimetics or inhibitors of the main GLP-1 degrading enzyme dipeptidyl peptidase 4 (DPP-4). Acute increases in GLP-1 activity abolish endothelial dysfunction induced by high-fat meals or by hyperglycemia. In vitro and preliminary clinical studies also indicate that GLP-1 or GLP-1 agonists can improve endothelial function by direct action on endothelium. GLP-1 or GLP-1 mimetic effects appear to extend to both conduit arteries and the microvasculature, and may depend on activation of endothelial GLP-1 receptors and downstream nitric oxide production. Additional studies are necessary to confirm improvement of endothelial function after prolonged treatment with incretin based medications as well as the cardiovascular benefit of these agents.

Dipeptidyl peptidase-4 (DPP-4) inhibitors enhance incretin actions and beta-cell function. Concurrently, sodium-glucose co-transporter 2 (SGLT2) inhibitors block renal glucose reabsorption promoting excretion. In this study, we investigated the effects of linagliptin (a DPP-4 inhibitor) and BI-38335 (an SGLT2 inhibitor), individually and in combination, on glucose homeostasis, islet function, and pancreatic islet morphology in db/db mice. Diabetic and non-diabetic mice received linagliptin (3 mg/kg), BI-38335 (1 mg/kg), the two drugs in combination or control once daily for 8 weeks. Blood glucose homeostasis and insulin sensitivity were assessed. Pancreatic islet function and morphology as well as inflammatory factors and toll like receptor 2 (TLR2) pathways involved in islet inflammation were investigated. Active treatments markedly reduced blood glucose and glycated hemoglobin A1c (HbA(1c)) levels, with the combined treatment showing the greater effects. Insulin resistance was improved in the BI-38335 and combination groups with the enhancement of insulin sensitivity and significant increase of serum adiponectin levels. The combined treatment exhibited greater effects on enhanced islet glucose-stimulated insulin secretion and improved glucose tolerance. Moreover, the combination restored the islet beta-/alpha-cell ratio, reduced beta-cell apoptosis, decreased expression of islet immune cell markers, and suppressed factors related to the TLR2 pathway. In addition, all active treatments reduced serum lipid profiles, though the combination produced more robust effects. Collectively, our data show that combined treatment with BI-38335 and linagliptin work, at least in part, synergistically to benefit islet cell function/architecture and insulin resistance, thus improving glycemic control.

Dipeptidyl peptidase -4 inhibitors represent a novel way to augment the incretin system and one of the newest class of medications in the treatment of type 2 diabetes mellitus. Their mechanism of action is to decrease the inactivation of glucagon-like peptide 1 and glucose-dependent insulinotropic polypeptide, both of which are involved in maintaining euglycemia subsequent to carbohydrate intake. Currently investigated agents include sitagliptin, vildagliptin, saxagliptin, linagliptin, and alogliptin. Each agent has been shown to provide significant improvements in glycemic control compared to placebo. They are effective when added to other oral diabetes agents and in the cases of sitagliptin, vildagliptin, and alogliptin in addition to insulin. These agents may not provide as significant improvement in glucose concentrations as some other medications including metformin, thiazolidinediones, or glucagon-like peptide 1 agonists. The lack of head to head clinical data comparing the various dipeptidyl peptidase 4 inhibitors does not allow for specific recommendations if one agent is more effective or safer than another within the class. Their side effect profile suggests they are very well tolerated and have few drug interactions. For patients with mildly elevated glucose concentrations, they are therapeutic options in both drug-naive patients as well as those not optimally controlled on other diabetes medications.

Dipeptidyl peptidase 4 (DPP-4), a substrate-specific serine protease, has been validated as a promising drug target for the treatment of type 2 diabetes. DPP-4 inhibitors significantly lowered blood glucose levels in patients with type 2 diabetes without common body weight gain, hypoglycemia and gastrointestinal disturbance side effects. Therefore, DPP-4 inhibitors attracted more and more attention. In particular, non-peptidomimetic DPP-4 inhibitors have been a focus of research and development and made great progress in recent years, which resulted in the discovery of a wide variety of potent non-peptidomimetic DPP-4 inhibitors. Some of them, such as sitagliptin, alogliptin and linagliptin have already been used as marketed drugs, while others have been into clinical trials. Based on the core structural features of non-peptidomimetic DPP-4 inhibitors, seven types were classified in the article. For each type, we focused on the description of strategies for design and optimization, together with a discussion on concluded structure-activity relationships (SAR). In addition, the contribution of specific substituents to the inhibition of DPP-4 was summarized. Selectivity towards the inhibition of DPP-4 over dipeptidyl peptidase 8 (DPP-8) and dipeptidyl peptidase 9 (DPP-9) was also presented.

Accelerated atherosclerosis and microvascular complications are the leading causes of coronary heart disease, end-stage renal failure, acquired blindness and a variety of neuropathies, which could account for disabilities and high mortality rates in patients with diabetes. Glucagon-like peptide-1 (GLP-1) belongs to the incretin hormone family. L cells in the small intestine secrete GLP-1 in response to food intake. GLP-1 not only enhances glucose-evoked insulin release from pancreatic β-cells, but also suppresses glucagon secretion from pancreatic α-cells. In addition, GLP-1 slows gastric emptying. Therefore, enhancement of GLP-1 secretion is a potential therapeutic target for the treatment of type 2 diabetes. Dipeptidyl peptidase-4 (DPP-4) is a responsible enzyme that mainly degrades GLP-1, and the half-life of circulating GLP-1 is very short. Recently, DPP-4 inhibitors and DPP-4-resistant GLP-1 receptor (GLP-1R) agonists have been developed and clinically used for the treatment of type 2 diabetes as a GLP-1-based medicine. GLP-1R is shown to exist in extra-pancreatic tissues such as vessels, kidney and heart, and could mediate the diverse biological actions of GLP-1 in a variety of tissues. So, in this paper, we review the pleiotropic effects of GLP-1-based therapies and its clinical utility in vascular complications in diabetes.