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Glucokinase-maturity-onset diabetes of the young (GCK-MODY) is caused by heterozygous inactivating mutations in glucokinase (GK, gene symbolGCK) and impaired glucose sensing. We investigated effects of dorzagliatin, a novel allosteric GK activator, on insulin secretion rates (ISR) and beta-cell glucose-sensitivity (βCGS) in GCK-MODY and recent-onset type 2 diabetes. In a double-blind, randomized cross-over study, eight participants with GCK-MODY and 10 with type 2 diabetes underwent 2-hour 12-mmol/L hyperglycemic clamps following a single oral dose of dorzagliatin 75mg or matched placebo. Effects of dorzagliatin on wild-type and mutant GK enzyme activity were investigated using a nicotinamide adenine dinucleotide phosphate (NADP+) coupled assay with glucose-6-phosphate dehydrogenase (G6PD) in vitro. In GCK-MODY, dorzagliatin significantly increased absolute and incremental second-phase ISR versus placebo but not the acute insulin response. Dorzagliatin improved βCGS in GCK-MODY with a upward and leftward shift in ISR-glucose response. Dorzagliatin increased basal ISR in type 2 diabetes with smaller changes in second-phase ISR compared with GCK-MODY. In vitro, dorzagliatin directly reduced the glucose half saturation concentration (S0.5) of wild-type GK and selected GK mutants to varying degrees. Dorzagliatin directly restored enzyme activity of select GK mutants and enhanced wild-type GK activity, thereby correcting the primary defect of glucose sensing in GCK-MODY.

We investigated the effect of tirzepatide (TZP) 15 mg (novel GIP-GLP-1 dual receptor agonist) , placebo and semaglutide 1 mg (SEMA) on beta-cell function using euglycaemic and hyperglycemic glucose clamps (EGC, HGC) and Mixed Meal Tolerance Tests (MMTT) in a 28-week double-blind randomized controlled trial of people with type 2 diabetes. During EGC and HGC, TZP improved insulin sensitivity (M-value) , first and second phase insulin secretion (ISR) and beta-cell glucose sensitivity (ratio of ISR and glucose increments) more than SEMA and placebo (Table; EASD symposium 2021) . During MMTT, both fasting and AUC glucose were reduced more with TZP than with SEMA or placebo, while incremental glucose AUC was reduced with TZP and SEMA vs. placebo similarly. Despite similarly reduced incremental glucose AUC, insulin AUC and incremental insulin AUC were reduced by TZP but not by SEMA. Model-derived beta-cell glucose sensitivity was increased with TZP and SEMA from baseline similarly. In contrast, ISR at 7.2 mmol/L glucose increased more with TZP than with placebo and SEMA (Table) . The glucose-lowering effect of TZP is mediated through improvements in multiple aspects of beta-cell function, including beta-cell glucose sensitivity and ISR, and in insulin sensitivity, resulting in pronounced lowering of fasting and postprandial glucose. These effects help explain the superior improvement in glucose control seen with TZP vs. comparators in clinical trials. Disclosure A. Mari: Consultant; Lilly. Research Support; Lilly. J. Li: Employee; Eli Lilly and Company. Stock/Shareholder; Eli Lilly and Company. S. Urva: Employee; Eli Lilly and Company. T. Heise: Advisory Panel; Novo Nordisk A/S. Research Support; ADOCIA, AstraZeneca, Biocon, Boehringer Ingelheim International GmbH, Crinetics Pharmaceuticals, Inc., Eli Lilly and Company, Gan & Lee Pharmaceuticals, Genova, Nestlé, Neuraly Inc., Novo Nordisk A/S, Sanofi, Zealand Pharma A/S. Speaker's Bureau; Eli Lilly and Company, Gan & Lee Pharmaceuticals, Novo Nordisk A/S. J. De Vries: Advisory Panel; ADOCIA, Novo Nordisk A/S, Zealand Pharma A/S. Speaker's Bureau; Novo Nordisk A/S. E.J. Pratt: Employee; Eli Lilly and Company. R.J. Heine: Employee; Eli Lilly and Company. M.K. Thomas: Employee; Eli Lilly and Company. Stock/Shareholder; Eli Lilly and Company. Z. Milicevic: Employee; Eli Lilly and Company. K.J. Mather: Employee; Eli Lilly and Company. Stock/Shareholder; Eli Lilly and Company. Funding Eli Lilly and Company

Glucokinase maturity onset diabetes of the young (GCK-MODY) is caused by heterozygous inactivating mutations in GCK that is not responsive to conventional glucose lowering drugs. We investigated the effects of dorzagliatin, a novel allosteric activator of hepatic and beta-cell GCK on insulin secretion rates (ISR) and glucose sensitivity (GS) in GCK-MODY and recent onset type 2 diabetes (T2D) . In a double-blind, randomized cross-over study, 8 GCK-MODY (mean±SD age 36.1­±6.4years) and T2D subjects (mean age 50.2±6.9 years, median T2D duration 0.90 [0.60-1.42] years) underwent 2-hour 12 mmol/L hyperglycemic clamps following a single oral dose of dorzagliatin 75mg or matched placebo. Insulin and C-peptide were measured. GCK-MODY group showed significantly higher absolute (mean±SD 432±85 versus 272±91 pmol/min/m2, p=0.002) and incremental (342­±91 vs. 241±74 pmol/min/m2, p=0.004) second-phase ISR following dorzagliatin versus placebo. Dorzagliatin significantly improved GS in GCK-MODY (51±21 vs. 33­±13 pmol/min/m2 per mmol/L p=0.028) with an upward and leftward shift in ISR-glucose response. In T2D, basal ISR was significantly improved following dorzagliatin (102±57 vs. 60±42, p=0.018) with smaller increases in second phase ISR and GS. Dorzagliatin improves second phase ISR and GS, with larger effects in GCK-MODY than T2D. Disclosure E.Chow: Research Support; Hua Medicine, Medtronic, Powder Pharmaceuticals Inc., Speaker's Bureau; Novartis AG, Sanofi. L.Chen: Employee; Hua Medicine. J.C.Chan: Board Member; Asia Diabetes Foundation, Consultant; Bayer AG, Boehringer Ingelheim International GmbH, Celltrion, Merck Sharp & Dohme Corp., Roche Diabetes Care, Viatris Inc., Research Support; Applied Therapeutics, AstraZeneca, Eli Lilly and Company, Hua Medicine, Servier Laboratories, Stock/Shareholder; GemVCare Ltd. K.Wang: None. C.K.P.Lim: None. S.Tsoi: None. B.Fan: None. A.Luk: None. R.C.Ma: Other Relationship; Bayer AG, Boehringer Ingelheim International GmbH, Research Support; AstraZeneca, Bayer AG, Novo Nordisk A/S, Pfizer Inc., Tricida, Inc. E.Ferrannini: Advisory Panel; Boehringer Ingelheim International GmbH, Novo Nordisk, Oramed Pharmaceuticals, Consultant; Elgia Therapeutics, Research Support; Janssen Research & Development, LLC, Oramed Pharmaceuticals, Sanofi-Aventis U.S., Speaker's Bureau; Boehringer Ingelheim International GmbH. A.Mari: Consultant; Lilly, Research Support; Lilly. Funding Hua Medicine Investigator Initiated Clinical Research

Tirzepatide (TZP) , a novel GIP-GLP-1 dual agonist, improved fasting measures of insulin sensitivity partially attributable to weight loss in Phase 2 studies. Studies in mice demonstrated that GIP receptor agonism with TZP improved insulin sensitivity independent of weight loss. To further evaluate insulin-sensitizing actions of TZP, we measured insulin sensitivity with hyperinsulinemic euglycemic clamps (M-value) in a 28-week double-blind randomized controlled trial comparing effects of TZP 15mg with placebo or semaglutide 1mg (SEMA) , a selective GLP-1RA, all subcutaneous QW. Linear regression was used to compare relationships of change in M-value versus change in weight across treatment groups. Change in M-value was related to absolute change and % change in weight (Figure) . Slopes of linear relationships with absolute and % weight change differed between TZP and SEMA (absolute change: p=0.015; % change: p=0.03) . Larger negative slopes were observed for TZP compared with SEMA on change in M-value related to absolute change and to % change in weight. These results suggest that TZP may provide greater improvement in insulin sensitivity than a selective GLP-1RA per unit weight loss, most evident in subjects with greater weight loss. Disclosure K.J.Mather: Employee; Eli Lilly and Company, Stock/Shareholder; Eli Lilly and Company. M.K.Thomas: Employee; Eli Lilly and Company, Stock/Shareholder; Eli Lilly and Company. A.Mari: Consultant; Lilly, Research Support; Lilly. J.Li: Employee; Eli Lilly and Company, Stock/Shareholder; Eli Lilly and Company. T.Heise: Advisory Panel; Novo Nordisk A/S, Research Support; ADOCIA, AstraZeneca, Biocon, Boehringer Ingelheim International GmbH, Crinetics Pharmaceuticals, Inc., Eli Lilly and Company, Gan & Lee Pharmaceuticals, Genova, Nestlé, Neuraly Inc., Novo Nordisk A/S, Sanofi, Zealand Pharma A/S, Speaker's Bureau; Eli Lilly and Company, Gan & Lee Pharmaceuticals, Novo Nordisk A/S. J.De vries: Advisory Panel; ADOCIA, Novo Nordisk A/S, Zealand Pharma A/S, Speaker's Bureau; Novo Nordisk A/S. S.Urva: Employee; Eli Lilly and Company. T.Coskun: Employee; Eli Lilly and Company. Z.Milicevic: Employee; Eli Lilly and Company. A.Haupt: Employee; Lilly, Stock/Shareholder; Lilly. Funding Eli Lilly and Company

Chronic hypertriglyceridemia is associated with reduced glucose tolerance. Whether this association is mediated by triglycerides or free fatty acids (FFA) and which mechanisms are involved is unclear. To examine the effect of excess triglycerides alone or combined with FFA, two matched groups of healthy volunteers underwent 5h IV infusions of either saline or Intralipid without (n=12) or with heparin (I+H; n=10), during which 3h oral glucose tolerance tests (OGTT) were performed. Plasma triglycerides reached similar high-physiological levels during both lipid infusions (~2.5 mmol/L) while FFAs were markedly higher during I+H (AUC 249 [130] vs. 77 [20] mmol/L, p=0.0001). At baseline, Intralipid reduced insulin clearance while I+H increased insulin secretion and reduced insulin sensitivity and clearance. Both lipid infusions impaired glucose tolerance. Intralipid inhibited glucose-stimulated insulin secretion (i.e., β-cell glucose sensitivity), stimulated potentiation, and reduced insulin sensitivity and clearance, while I+H induced a greater impairment in insulin sensitivity but enhanced the dynamic component of insulin secretion (i.e., β-cell rate sensitivity). Acute hypertriglyceridemia impairs glucose tolerance in healthy subjects by reducing insulin sensitivity and β-cell glucose sensitivity. A concomitant increase in FFA further reduces insulin sensitivity while enhancing β-cell function. Disclosure D. Trico: None. B. D. Astiarraga: None. M. Seghieri: None. A. Mengozzi: None. S. Baldi: None. A. Mari: Research Support; Self; Eli Lilly and Company. A. Natali: None. Funding European Foundation for the Study of Diabetes

Proinsulin (PI) processing is altered in beta-cells during T2D progression. However, the molecular mechanisms driving such alterations are not fully characterized neither their occurrence were correlated with patients’ metabolic profile. To fill this gap, we investigated the correlation between pancreatic proinsulin (PI) expression and phenotypic/functional changes of beta-cells during metabolic stress in extensively clinical characterized impaired glucose tolerant (IGT, n=7) and T2D (n=4) individuals, compared to normal glucose tolerant (NGT, n=4). We analyzed microdissected pancreatic islets collected from surgical pancreas biopsies. The expression of genes associated to ER stress and β cell phenotype were evaluated. Given the high heterogeneity among pancreatic islets, we also performed a single islets analysis in n=88 islets from n=3 NGT, n=3 IGT and n=3 T2D patients. PDIA1, GRP78 and XBP1 genes, involved in unfolded protein response (UPR), were significantly upregulated in pancreatic islets of IGT and T2D patients vs. NGT (p Disclosure N. Brusco: None. C. Cefalo: None. U. Capece: None. F. Impronta: None. A. Mari: Research Support; Self; Eli Lilly and Company. F. Dotta: None. A. Giaccari: None. T. Mezza: None. G. Sebastiani: None. G. Licata: None. G. E. Grieco: None. G. Di giuseppe: None. L. Nigi: None. D. Fignani: None. S. Moffa: None. F. Cinti: None. Funding Università Cattolica del Sacro Cuore (FondiAteneo Linea D.1, anno 2020); Italian Ministry of Education, University and Research (GR-2018-12365577); European Foundation for the Study of Diabetes; AstraZeneca

We compared 3-hr OGTT model-derived measures of insulin sensitivity and β-cell function after 12 mo treatment with placebo (PLAC), metformin (MET), liraglutide plus MET (L+M), 3 mo glargine followed by 9 mo MET (G/M) and gastric banding (GB) in adults with IGT or T2D in the Restoring Insulin Secretion (RISE) Study. Modeling parameters included insulin sensitivity (OGIS), insulin secretion rate (ISR) at reference glucose 6.5 mM (ISR@6.5), total integrated ISR (tISR), glucose sensitivity (GS: slope ISR vs. glucose concentration) and rate sensitivity (RS: ISR relative to glucose rate of change). Adjusted linear mixed models compared model parameters over time within and between each study arm. Results: Baseline model parameters did not differ by treatment arm. OGIS increased in all groups except PLAC. ISRs and GS increased in L+M but decreased or were unchanged in the other treatment arms. RS only increased in the G/M and GB arms. Treatment effects differed by arm. For L+M, GS and ISRs were increased vs. all other arms. For GB, RS was increased and tISR decreased vs. PLAC and GS was increased vs. MET. In summary, L+M augments insulin secretion and increases GS, while GB increases RS. Clinically, both L+M and GB appear to improve β-cell function at 12 mo and may benefit adults with IGT or recent-onset T2D while on treatment. Disclosure K. Utzschneider: Other Relationship; Self; Medtronic. L. El Ghormli: None. S. Sam: None. D.A. Ehrmann: None. K.J. Mather: Research Support; Self; Abbott, Merck & Co., Inc., Novo Nordisk Inc., Sanofi. E. Barengolts: None. T.S. Hannon: None. M. Tripputi: None. S. Edelstein: None. A. Mari: Consultant; Self; Lilly Diabetes. Research Support; Self; Boehringer Ingelheim International GmbH. T. Consortium: None. Funding American Diabetes Association (1-14-RISE-01); National Institute of Diabetes and Digestive and Kidney Diseases

Increased circulating levels of proinsulin (PI) and proinsulin-to-insulin ratio (PI/INS) is a well-known abnormality in type 2 diabetes (T2D). The exact mechanism behind this increase in T2D, as well as in T1D, is unknown. The aim of this study was to analyze proinsulin and insulin expression in pancreatic islets of tissue biopsies of patients undergoing partial pancreatectomy (PP) with normal glucose tolerance (NGT), impaired glucose tolerance (IGT) and T2D, in order to explore the alterations that occur in islets during metabolic stress. Frozen sections of pancreatic tissue biopsies (n=17) classified following OGTT into n=5 NGT, n=9 IGT and n=3 T2D were stained for INS and PI through double immunofluorescence staining. β-cell glucose sensitivity (calculated as the ratio of insulin secretion and glucose increments), basal insulin secretion, and glucose levels 2-hours following OGTT were analyzed. Image analysis was performed on each individual islet through Volocity software. In-situ staining measurements were correlated with patients’ clinical parameters. PI-INS colocalization as well as the area (µm2) of PI positivity and PI/INS ratio gradually increased from NGT to IGT and T2D pancreatic islets (p In conclusion, our results suggest that the increase of PI/INS ratio in pancreatic islets is directly related to metabolic defects in dysfunctional β cells, highlighting the importance of correct PI processing and folding in the maintenance of glucose homeostasis. Disclosure N. Brusco: None. G. Sebastiani: None. G. Licata: None. G.E. Grieco: None. L. Nigi: None. D. Fignani: None. S. Moffa: None. G. Sorice: None. G. Di Giuseppe: None. C. Cefalo: None. A. Mari: Consultant; Self; Lilly Diabetes. Research Support; Self; Boehringer Ingelheim International GmbH. F. Dotta: None. A. Giaccari: Speaker’s Bureau; Self; Amgen, AstraZeneca, Eli Lilly and Company, Merck Sharp & Dohme Corp., Mundipharma, Novo Nordisk A/S, Sanofi-Aventis. T. Mezza: None. Funding European Foundation for the Study of Diabetes; AstraZeneca

PCSK9 inhibitors are monoclonal antibodies effective in reducing LDL-C and cardiovascular events by neutralizing circulating PCSK9. Since PCSK9 is also expressed in other organs, including pancreas, studies on PCSK9 KO mice, have shown impaired insulin secretion. Other murine models in which PCSK9 was silenced only in the liver (mimicking the action of PCSK9i) had normal glucose metabolism. The aim of our study was to evaluate the effect of PCSK9 inhibitors on glucose metabolism and beta cell function in humans. 11 nondiabetic subjects candidate for PCSK9i therapy were enrolled in the study. All subjects underwent an OGTT at baseline and after 6 months of therapy, at which point surrogate insulin sensitivity indices were obtained (Matsuda; OGIS). During OGTT, insulin secretion parameters were derived from C-peptide levels by deconvolution; we evaluated basal insulin secretion rate, total insulin secretion rate and β-cell glucose sensitivity, for 6 of the 11 enrolled subjects. All patients showed a 53.3% reduction in LDL cholesterol after 6 months of therapy; the mean LDL-C baseline level (B) was 202.5 ± 45 mg/dl, while mean LDL-C post therapy (PT) value was 94.6 ± 27 mg/dl. Glycemic and insulinemic curves showed no significant differences between baseline and follow-up. Matsuda index (B 4.1 ± 1, PT 3.4 ± 0.7 mL min-1kg-1) and OGIS (B 396.9 ± 32, PT 386.2 ± 28 ml min-1m-2), showed no differences between baseline and post-therapy evaluation. There were no significant differences in insulin secretion parameters: basal insulin secretion rate (B 63.7 ± 34, PT 66.4 ± 23 pmol min-1m-2), total insulin secretion rate (B 48.7 ± 17, PT 46.9 ± 16, nmol m-2) and β-cell glucose sensitivity (B 117.5 ± 69, PT 141.2 ± 47 pmol min-1m-2mM-1) obtained from c-peptide deconvolution. Our study, although preliminary and in a small sample of patients, suggests that PCSK9is does not cause alterations in glucose metabolism and beta cell function. Further studies and a longer follow-up may provide us with further data to confirm our observations. Disclosure S. Moffa: None. T. Mezza: None. C. Cefalo: None. F. Cinti: None. G. Sorice: None. F. Impronta: None. U. Capece: None. A. Mari: Consultant; Self; Lilly Diabetes. Research Support; Self; Boehringer Ingelheim International GmbH. A. Giaccari: Speaker’s Bureau; Self; Amgen, AstraZeneca, Eli Lilly and Company, Merck Sharp & Dohme Corp., Mundipharma, Novo Nordisk A/S, Sanofi-Aventis.

β-cell functional defects temporally anticipate (and eventually cause) the subsequent development of hyperglycemia, whereas a significant reduction (∼50%) of beta-cell mass is observed at diagnosis of T2D. To further investigate the relative role of beta-cell mass reduction/dysfunction in the development of T2D, we performed, pre- and post-surgery, oral glucose tolerance tests (OGTT) and hyperglycemic clamps (HC), followed by arginine stimulation and mixed meal test (MMT), in 39 patients undergoing pancreatoduodenectomy (PD), as model of acute mass reduction. Based on post-surgery OGTT, subjects were divided into 3 groups depending on glucose tolerance: normal (NGT, n=11), impaired (IGT, n=10) or diabetic (DM, n=18) (23 F/16 M, 63±13.7 yrs, BMI 23.9±4.5 kg/m2). To evaluate β-cell function, β-cell glucose sensitivity (GS) was calculated during HC, MMT e OGTT as the ratio of insulin secretion (IS) and glucose increments. Comparison among the 3 groups revealed that PD had a significantly different effect on time-dependent change of glucose and insulin levels during all tests (P Disclosure T. Mezza: None. P. Ferraro: None. G. Di Giuseppe: None. C. Cefalo: None. S. Moffa: None. G. Quero: None. F. Cinti: None. F. Impronta: None. U. Capece: None. S. Alfieri: None. A. Mari: Consultant; Self; Lilly Diabetes. Research Support; Self; Boehringer Ingelheim International GmbH. A. Giaccari: Speaker’s Bureau; Self; Amgen, AstraZeneca, Eli Lilly and Company, Merck Sharp & Dohme Corp., Mundipharma, Novo Nordisk A/S, Sanofi-Aventis.

Loss of β-cell function is critical in the pathogenesis of T2D and may progress more rapidly in youth. We compared 3-hr OGTT model-derived measures of β-cell function in youth and adults with IGT or T2D in RISE treated for 12 mo with metformin (MET), or glargine followed by metformin (G/M) and 9 mo after treatment withdrawal. Model parameters included insulin sensitivity (OGIS), insulin secretion rate (ISR) at glucose 6.5 mM (ISR-6.5), total ISR (tISR), glucose sensitivity (GS: slope ISR vs. glucose concentration) and rate sensitivity (RS: ISR relative to glucose rate of change). Linear mixed models tested for differences by time (0-12 and 0-21 mo), age (youth vs. adults) and treatment (MET vs. G/M). Key observations included the following. Insulin sensitivity (OGIS) increased transiently in all but adults on G/M. In youth, insulin secretion (ISR-6.5 and tISR) and RS decreased relative to baseline, with GS also decreased in the G/M arm. In contrast, in adults there were no significant changes in modeled parameters at 21 mo. Insulin secretion and β-cell function parameters decreased more in youth vs. adults in the G/M arm. By treatment, GS decreased more in the G/M vs. MET arm in youth, but there were no differences in adults. In conclusion, only youth exhibited worsening of features of β-cell function that can only be derived with mathematical modeling. Disclosure K. Utzschneider: Other Relationship; Self; Medtronic. M. Tripputi: None. M. Cree-Green: Advisory Panel; Self; Novo Nordisk Inc. T.S. Hannon: None. K.J. Nadeau: None. E. Barengolts: None. J.P. Palmer: None. K.J. Mather: Research Support; Self; Abbott, Merck & Co., Inc., Novo Nordisk Inc., Sanofi. S. Caprio: None. S. Edelstein: None. A. Mari: Consultant; Self; Lilly Diabetes. Research Support; Self; Boehringer Ingelheim International GmbH. T. Consortium: None. Funding American Diabetes Association (1-14-RISE-01); National Institute of Diabetes and Digestive and Kidney Diseases

Background: The glucosuria induced by sodium-glucose cotransporter-2 inhibitors (SGLT2i) stimulates endogenous (hepatic) glucose production (EGP) blunting the decline in HbA1c. We hypothesized that, in response to glucosuria, a renal signal is generated and stimulated EGP. Aim: To examine the effect of acute administration of dapagliflozin (DAPA) in nondiabetic, renal transplant subjects on SGLT2i-induced stimulation of EGP. Methods: 20 subjects [10 with intact native kidneys (IK) and 10 with bilateral nephrectomy (NK)] underwent measurement of EGP ([6,6-2H2]-glucose) before and for 6 hours after administration of DAPA or placebo (PLC) on 2 separate days. Results: DAPA induced greater glucosuria in subjects with IK versus NK (8.6±1.1 vs. 5.5±0.5 grams/6-hrs; p=0.02). During 6-hour, plasma glucose decreased slightly and similarly in both groups, with no difference compared to PLC. Following PLC, there was a progressive time-related decline in EGP that was similar in both groups. Following DAPA, EGP declined in both groups but the decrement in EGP was 56% greater in the NK. During DAPA, urinary glucose excretion was correlated with EGP (r = 0.34, p Conclusions: In NK subjects the hepatic compensatory response to acute SGLT2i-induced glucosuria was attenuated compared to diabetic subjects with IK, suggesting a SGLT2i-mediated stimulation of hepatic glucose production via efferent renal nerves in an attempt to compensate for the urinary glucose loss, i.e., a renal-hepatic axis. Disclosure G. Daniele: None. C. Solis-Herrera: Consultant; Self; Lexicon Pharmaceuticals, Inc. A. Dardano: None. A. Mari: Consultant; Self; Lilly Diabetes. Research Support; Self; Boehringer Ingelheim International GmbH. A. Tura: None. L. Giusti: None. J.J. Kurumthodathu: None. A.A.G. Brocchi: None. B. Campi: None. A. Saba: None. A. Bianchi: None. C. Tregnaghi: None. M. Egidi: None. M. Abdul-Ghani: None. R.A. DeFronzo: None. S. DelPrato: None.

Increased proinsulin secretion, which characterizes type 2 diabetes and insulin resistance, may be due to an intrinsic, primitive defect in proinsulin processing or be secondary to increased demand on β-cells (hyperinsulinemia secondary to insulin resistance). An alternative way to investigate the relation between relative hyperproinsulinemia and increased secretory demand is to study the dynamic changes in the proinsulin-to-insulin ratio after partial pancreatectomy, a model of acute increased β-cell workload on the remaining pancreas. To pursue this aim, patients without diabetes, scheduled for partial pancreatectomy, underwent 4-h mixed-meal tests and hyperinsulinemic-euglycemic clamps before and after surgery. After acute β-cell mass reduction, no changes were observed in the fasting proinsulin-to-insulin ratio, whereas the fold change in the proinsulin-to-insulin ratio significantly increased over time after the meal. Further, our data demonstrate that whole-body insulin resistance is associated with underlying defects in proinsulin secretion, which become detectable only in the presence of increased insulin secretion demand.

Plasma proteins can provide valuable insights on human health and disease states. Within the framework of the EU IMI project DIRECT (https://www.direct-diabetes.org), we used a set of affinity proteomic methods to profile > 3100 study participants at baseline. Multiplexed assays quantified more than 600 unique proteins in EDTA plasma from this multi-center cohort that included 2300 subjects at risk of developing T2D (HbA1c ~ 6-6.5%) as well as 800 with early T2D (HbA1c > 6.5%). Using extensive clinical and other omics metadata available, the aim of the investigation was to identify plasma proteins associated with baseline traits. An initial analysis highlighted the importance of considering sample-related and pre-analytical variables as possible confounders in the data analysis. Hence, we used linear mixed models that included several parameters such as age, sex, study center and collection date. Next, we defined proteins associating with any of the >50 quantitative clinical traits at baseline. We found more than 300 proteins in plasma that were associated with diabetes related traits (adjusted p-value < 0.0001), many of which were prominently associated with BMI. The shortlisted candidates included leptin which associates with waist circumference and BMI; IGFBP1 and IGFBP2 to Matsuda; adiponectin to basal insulin secretion rate and fasting HDL; LDL receptor proteins to fasting triglycerides; APOM to fasting cholesterol; or IL8 and MCP-1 to fasting AST. In addition, we performed pQTL analysis to assess any connection between the protein values in plasma and genetic variants. We observed >400 cis-pQTLs (q-value < 0.05), such as for APOM (rs2736163, p = 5.15 e-24), which illustrated that many of the studied protein profiles are affected by a genetic component. With follow-up samples collected 3-4 years after starting the study, the baseline values will serve as valuable indicators of progression and allow study of how each participant's disease phenotype changes over time or due to treatment. Disclosure M. Hong: None. A. Viñuela: None. R.S. Häussler: None. M. Dale: None. R.W. Koivula: None. J. Fernandez-Tajes: None. A. Mahajan: None. R. Bizzotto: Research Support; Self; GlaxoSmithKline plc. A. Mari: Consultant; Self; Eli Lilly and Company. Research Support; Self; Boehringer Ingelheim International GmbH. E. Dermitzakis: Advisory Panel; Self; DNAnexus LTD. Board Member; Self; Hybridstat LTD. M. McCarthy: Advisory Panel; Self; European Association for the Study of Diabetes, Pfizer Inc. Consultant; Self; Eli Lilly and Company, Merck & Co., Inc. Consultant; Spouse/Partner; Merck & Co., Inc. Research Support; Self; AbbVie Inc., Boehringer Ingelheim International GmbH. Research Support; Spouse/Partner; Diabetes UK. Research Support; Self; Janssen Pharmaceuticals, Inc., Merck & Co., Inc., National Institutes of Health. Research Support; Spouse/Partner; National Institutes of Health. Research Support; Self; Novo Nordisk A/S. Research Support; Spouse/Partner; Novo Nordisk A/S. Research Support; Self; Novo Nordisk Foundation, Roche Pharma, Sanofi-Aventis, Servier, Takeda Pharmaceutical Company Limited. P.W. Franks: Board Member; Self; Zoe Ltd. Research Support; Self; AstraZeneca, Boehringer Ingelheim International GmbH, Lilly Diabetes, Novo Nordisk A/S, Novo Nordisk Foundation, Sanofi, Servier. E. Pearson: None. J.M. Schwenk: None. Funding Innovative Medicines Initiative Joint Undertaking (115317)

Background: Mild hypertriglyceridemia is associated with reduced glucose tolerance and increased risk of type 2 diabetes, independent of obesity and insulin sensitivity, in cross-sectional and prospective studies. To what extent these effects are directly produced by triglycerides and which are the major glucose homeostatic mechanisms involved is unclear. Methods: We examined the effects of acute triglyceride elevation on tracer-derived glucose metabolic fluxes, model-derived β-cell function, insulin sensitivity, and insulin clearance during two 3-h oral glucose tolerance tests with infusion of either normal saline or 20% Intralipid (25 ml/min/m2, without heparin) in 8 healthy lean volunteers. Results: A 2-h Intralipid infusion increased plasma TG by 2.7-fold (from 52±7 to 192±29 mg/dl; p=0.0003) without affecting plasma FFA, glucose, or insulin levels. After glucose ingestion, the lipid infusion elicited a marked increase in plasma glucose (iAUC +60%, p=0.01) and insulin (iAUC +52%, p=0.02) levels, while FFA were similarly suppressed. The deterioration in glucose tolerance was associated with reduced insulin sensitivity (Matsuda index -22%, p=0.04) and glucose clearance (-16%, p Conclusions: Mild acute hypertriglyceridemia, independent of FFA, impairs glucose tolerance in healthy subjects by reducing insulin sensitivity and glucose clearance. The magnitude of these effects on glucose tolerance exceeds that of hyperinsulinemia resulting from enhanced β-cell potentiation and reduced insulin clearance. Disclosure D. Trico: None. A. Mengozzi: None. M. Seghieri: None. A. Mari: Consultant; Self; Eli Lilly and Company. Research Support; Self; Boehringer Ingelheim International GmbH. A. Natali: None. Funding Italian Society of Diabetology; European Foundation for the Study of Diabetes

The Restoring Insulin Secretion (RISE) Study found that compared to adults (A), youth (Y) with early DM (33 Y, 104 A) or IGT (53 Y, 250 A) have higher insulin and C-peptide responses, even after adjusting for differences in insulin sensitivity. To better understand these differences, we compared mathematical modeling data from OGTTs to those from a hyperglycemic clamp within the RISE Study. Modeled measures were the dose-response relationship between glucose and insulin secretion (glucose sensitivity [GS], rate sensitivity [RS]) and the oral glucose insulin sensitivity index (OGIS). Clamp measures were insulin sensitivity (steady state glucose infusion rate/insulin [M/I]), acute (0-10 minutes) C-peptide (ACPRg) and insulin (AIRg) responses to glucose, steady-state C-peptide (SSCP) at plasma glucose of 11.1 mmol/L, and arginine-stimulated maximum C-peptide (ACPRmax) response at glucose >25 mmol/L. Linear regression models were fit to assess relationships between OGTT model and clamp measures by age group. GS (r2 = 0.29, p Disclosure K. Utzschneider: Consultant; Self; Novo Nordisk Inc. A. Mari: Consultant; Self; Eli Lilly and Company. Research Support; Self; Boehringer Ingelheim International GmbH. M. Tripputi: None. K.J. Mather: Advisory Panel; Self; Roche Diabetes Care. Research Support; Self; Abbott, Merck & Co., Inc., Novo Nordisk A/S, Sanofi. K.J. Nadeau: None. S. Edelstein: None. T.S. Hannon: Advisory Panel; Self; Eli Lilly and Company. S.A. Arslanian: None. M. Cree-Green: None. T.A. Buchanan: Research Support; Self; Allergan, Apollo EndoSurgery. S. Caprio: None. S.E. Kahn: Advisory Panel; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company, Intarcia Therapeutics, Inc., Janssen Pharmaceuticals, Inc., Merck & Co., Inc., Novo Nordisk A/S. Consultant; Self; Neurimmune. Other Relationship; Self; Boehringer Ingelheim Pharmaceuticals, Inc., Merck & Co., Inc., Novo Nordisk A/S. R. Consortium: None. Funding American Diabetes Association (1-14-RISE-01 to S.E.K.); National Institute of Diabetes and Digestive and Kidney Diseases

Aims: Ataxia telangiectasia (A-T) is a rare genetic condition associated with diabetes. OGTT data show that nondiabetic adults with A-T are insulin resistant. ATM-ko mice are glucose intolerant, insulin resistant with abnormal fat distribution, which improve with TZD treatment. The RAMP study assessed the effects of pioglitazone in A-T. Methods: This open label, non-randomised, crossover study compared 8 nondiabetic people with A-T and 15 healthy controls. Dual tracer mixed meal tests, indirect calorimetry, and adipocyte function were used to assess response to treatment. Results: Groups were matched for age, BMI and HbA1c. Pioglitazone reduced fasting (61 [IQR 26 - 135] to 28.0 [IQR 20.9 - 110.1] pmol/l, p=0.008) and meal (393 [IQR 275 - 2103] to 252 [IQR 195 - 823], p=0.02) insulin in the A-T group, with unchanged fasting but reduced mean glucose (6.3 [IQR 6.1 - 6.7] to 5.9 [IQR 5.7 - 6.2] mmol/l, p=0.02). Pioglitazone did not affect glucose or insulin in controls. Pioglitazone improved insulin sensitivity in the A-T group, with reduced HOMA-IR (2.19 [IQR 0.96 - 4.14] to 0.97 [IQR 0.76 - 3.54], p=0.023) and increased Matsuda index (2.7 [IQR 1.2 - 5.9] to 5.3 [IQR 1.6 - 7.1], p=0.008). Pioglitazone increased adiponectin in both groups (A-T: 2528 [IQR 2008 - 4887] to 12461 [IQR 4451 - 15843] ng/ml, p=0.008; control 6262 [IQR 4051 - 89940] to 15123 [IQR 9594 - 19384] ng/ml, p=0.001). NEFAs were reduced in A-T (0.25 [IQR 0.22 - 0.28] to 0.18 [IQR 0.14 - 0.20] mmol/l, p=0.016). Pioglitazone increased the fasting respiratory quotient (RQ) in A-T (0.9 [IQR 0.8 - 1.0] to 1.1 [IQR 1.0 - 1.2], p=0.04). A mixed effects model of insulin sensitivity identified a significant gene * drug interaction (p=0.001) between A-T and pioglitazone. Conclusion: Pioglitazone treatment improved insulin sensitivity and adipocyte function in A-T. Pioglitazone reduced NEFAs and increased RQ, indicating a reduction in fatty acid oxidation. These data suggest that pioglitazone may be an appropriate first line treatment for diabetes in A-T. Disclosure L.J. McCreight: None. A. Mari: Consultant; Self; Eli Lilly and Company. Research Support; Self; Boehringer Ingelheim International GmbH. E. Pearson: None. Funding UK Wellcome Trust (to E.P.)

Bariatric surgery results in notable weight loss and alleviates hyperglycemia in patients with type 2 diabetes (T2D). We aimed to characterize the vascular effects of a mixed meal and infusion of exogenous glucose-dependent insulinotropic polypeptide (GIP) in the splanchnic region in 10 obese patients with T2D before and after bariatric surgery and in 10 lean control subjects. The experiments were carried out on two separate days. Pancreatic and intestinal blood flow (BF) were measured at baseline, 20 min, and 50 min with 15O-water by using positron emission tomography and MRI. Before surgery, pancreatic and intestinal BF responses to a mixed meal did not differ between obese and lean control subjects. Compared with presurgery, the mixed meal induced a greater increase in plasma glucose, insulin, and GIP concentrations after surgery, which was accompanied by a marked augmentation of pancreatic and intestinal BF responses. GIP infusion decreased pancreatic but increased small intestinal BF similarly in all groups both before and after surgery. Taken together, these results demonstrate that bariatric surgery leads to enhanced splanchnic vascular responses as a likely consequence of rapid glucose appearance and GIP hypersecretion.

Classic Ketogenic Diet (KD) is a high-fat, low-carbohydrate diet that induces ketone body production through fat metabolism with the goal of mimicking a starvation state without depriving the body of necessary calories. KD is an established treatment of glucose transporter type 1 deficiency syndrome and drug-resistant epilepsy, and it is currently evaluated in the management of insulin resistant states as metabolic syndrome, obesity and type 2 diabetes. Insulin is required for effective storage of meal substrates, but insulin secretory rate (ISR) response after a classic ketogenic meal (cKDm) has never been investigated We measured ISR after a cross-over administrations of a cKDm and of a Mediterranean meal (Mm) providing 2%vs60% carbohydrates, 88%vs25%fat and 10%vs15% protein, respectively of 40% of individual’s total energy requirement in 12 healthy subjects (6F/6M, 19-31 year. Venous blood was sampled at 0, 10, 20, 30, 45, 60, 90, 120 and 180min to measure glucose, insulin and C-peptide concentrations. ISR was calculated from c-peptide deconvolution and normalized to estimated body surface area Glucose and insulin concentrations and ISR responses were markedly reduced (p For the first time we have shown that cKDm is disposed with only a minimal ISR compared to a Mm. This finding may be of interest for patients with insulin resistance and or insulin secretory defects. Disclosure S. Bertoli: None. A. Spadafranca: None. R. De Amicis: None. A. Leone: None. A. Mari: None. A. Battezzati: None.

Nondiabetic insulin-resistant subjects (InsRes) display an increased α-cell mass, suggesting a key role of α-cells in the compensatory mechanisms to cope with insulin resistance states. The mechanism contributing to greater GLP-1 secretion detected in healthy patients following pancreatoduodenectomy (PD), is not fully understood and suggests other potential sources of the incretin hormone, such as α-cells. To investigate the dynamic changes of in-vivo GLP-1 secretion, insulin secretion (IS), and incretin effect (IE), 16 nondiabetic patients (10 F/6 M, 51±15 years.) scheduled for PD underwent a mixed meal test (MMT), a 2-h hyperglycemic clamp (HC), and a hyperinsulinemic euglycemic clamp (HEC) before and after surgery. β-cell glucose sensitivity (GS) was calculated as the ratio of IS and glucose increments, both during HC and MMT. The IE was estimated as the ratio of GS during the HC and MMT. InsRes displayed a reduction in the 1st IS at baseline (p=0.04), which did not decrease following PD. Both groups experienced a reduction of 2nd phase ISR (p Disclosure T. Mezza: None. S. Moffa: None. G. Sorice: None. C. Cefalo: None. F. Cinti: None. A. Mari: None. A. Giaccari: Advisory Panel; Self; Sanofi-Aventis. Speaker's Bureau; Self; AstraZeneca, Merck Sharp & Dohme Corp., Amgen Inc..

Gastric bypass surgery (RYGB) leads to improvement or remission of type 2 diabetes (T2D). Long-term studies indicate that the remission rate is higher 2 than 10 years post-surgery; whether the positive effects of surgery on ß-cell function (ß-GS) and glucose metabolism are maintained long term after surgery has not been determined. We studied 21 patients (12 T2D and 9 nondiabetic (ND)) before (B), 1 (1y) and 7 years (7ys) after RYGB with the use of a mixed meal test (MTT) in combination with glucose tracers to measure postmeal glucose fluxes and a euglycemic insulin clamp for insulin sensitivity (M). ß-GS (insulin secretion and dose response curve) was assessed by mathematical modelling. Weight loss 1y after RYGB was 30% and 35% of initial weight for ND and T2D respectively, and 24% and 30% at 7ys. T2D was resolved 1y post surgery in T2D and this outcome was maintained at 7ys (HbA1c 58±4 vs. 35±1 vs. 41±2 mmol/mol; B, 1y and 7ys). M value improved at 1y in proportion to the weight lost (5.0±0.8 to 7.2±0.7 in ND, and 4.3±0.8 to 7.5±0.7 mg. kgffm-1. min-1 in T2D, p Conclusion: In both ND and T2D, RYGB induces marked improvements in glucose tolerance, insulin sensitivity (both muscle and hepatic) and ß-cell function that are maintained 7 years after surgery. Disclosure S. Camastra: None. B.D. Astiarraga: None. C. Barbieri: None. M. Gaggini: None. M. Palumbo: None. R. Berta: None. D. Ciociaro: None. M. Anselmino: None. A. Mari: None. E. Ferrannini: None. A. Gastaldelli: Advisory Panel; Self; Gilead Sciences, Inc.. Other Relationship; Self; European Foundation for the Study of Diabetes. Consultant; Self; INVENTIVA SA.

Increasing scientific evidences support the hypothesis that type 2 diabetes mellitus (T2D) increases the risk of developing dementia and cognitive impairment. Experimental data, although still conflicting, show that insulin resistance (IR) is able to influence cognitive performance (CP). The objective of our study, therefore, was to verify the relationship between insulin resistance and cognitive performance (PC) in subjects at risk for DM2. For this reason 134 (111 F) volunteers, healthy at risk for diabetes mellitus (overweight and/or fasting hyperglycemia and/or family history for T2D), 39.0±12.3 year old, BMI 25.2±4.8 kg/m2, were enrolled; they underwent to metabolic study (OGTT for glycemia, insulinemia and c-peptide), and neuropsychological tests to evaluate global cognitive function, verbal learning, memory, visual attention and executive functions. The results of the neuropsychological tests were subsequently normalized by age and education; each test was standardized with a score from 0 (worst) to 4 (best performance). The equivalent scores of each test were summed to obtain a composite endpoint (Cognitive Performance Index), from 0 to 16, with increasing gradient for better CP.By dividing the subjects recruited into quartiles on the basis of PCI, the IR indexes gradually worsened as PCI became worse, particularly HOMA-IR, Matsuda, basal insulin secretion and basal insulin clearance (p These data seem to reinforce the hypothesis that insulin resistance, independently of glycemia, can worsen performance even in Health subjects, at risk for diabetes mellitus. Disclosure G. Sorice: None. I. Improta: None. T. Mezza: None. S. Grioni: None. G. Masone Iacobucci: None. S. Moffa: None. A. Mari: None. C. Marra: None. A. Giaccari: Advisory Panel; Self; Sanofi-Aventis. Speaker's Bureau; Self; AstraZeneca, Merck Sharp & Dohme Corp., Amgen Inc..

Pharmacologically induced glycosuria elicits adaptive responses in glucose homeostasis and hormone release. In type 2 diabetes (T2D), along with decrements in plasma glucose and insulin levels and increments in glucagon release, sodium–glucose cotransporter 2 (SGLT2) inhibitors induce stimulation of endogenous glucose production (EGP) and a suppression of tissue glucose disposal (TGD). We measured fasting and postmeal glucose fluxes in 25 subjects without diabetes using a double glucose tracer technique; in these subjects and in 66 previously reported patients with T2D, we also estimated lipolysis (from [2H5]glycerol turnover rate and circulating free fatty acids, glycerol, and triglycerides), lipid oxidation (LOx; by indirect calorimetry), and ketogenesis (from circulating β-hydroxybutyrate concentrations). In both groups, empagliflozin administration raised EGP, lowered TGD, and stimulated lipolysis, LOx, and ketogenesis. The pattern of glycosuria-induced changes was similar in subjects without diabetes and in those with T2D but quantitatively smaller in the former. With chronic (4 weeks) versus acute (first dose) drug administration, glucose flux responses were attenuated, whereas lipid responses were enhanced; in patients with T2D, fasting β-hydroxybutyrate levels rose from 246 ± 288 to 561 ± 596 µmol/L (P < 0.01). We conclude that by shunting substantial amounts of carbohydrate into urine, SGLT2-mediated glycosuria results in a progressive shift in fuel utilization toward fatty substrates. The associated hormonal milieu (lower insulin-to-glucagon ratio) favors glucose release and ketogenesis.

High-carbohydrate diets have been associated with β-cell strain, dyslipidemia, and endothelial dysfunction. We examined how β-cell and endothelial function adapt to carbohydrate overloading and the influence of insulin resistance. On sequential days in randomized order, nondiabetic subjects (classified as insulin-sensitive [IS] [n = 64] or insulin-resistant [IR] [n = 79] by euglycemic clamp) received four mixed meals over 14 h with either standard (300 kcal) or double carbohydrate content. β-Cell function was reconstructed by mathematical modeling; brachial artery flow-mediated dilation (FMD) was measured before and after each meal. Compared with IS, IR subjects showed higher glycemia and insulin hypersecretion due to greater β-cell glucose and rate sensitivity; potentiation of insulin secretion, however, was impaired. Circulating free fatty acids (FFAs) were less suppressed in IR than IS subjects. Baseline FMD was reduced in IR, and postprandial FMD attenuation occurred after each meal, particularly with high carbohydrate, similarly in IR and IS. Throughout the two study days, higher FFA levels were significantly associated with lower (incretin-induced) potentiation and impaired FMD. In nondiabetic individuals, enhanced glucose sensitivity and potentiation upregulate the insulin secretory response to carbohydrate overloading. With insulin resistance, this adaptation is impaired. Defective suppression of endogenous FFA is one common link between impaired potentiation and vascular endothelial dysfunction.

Using the hyperglycemic and euglycemic clamp, we demonstrated impaired β-cell function in obese youth with increasing dysglycemia. Herein we describe oral glucose tolerance test (OGTT)-modeled β-cell function and incretin effect in obese adolescents spanning the range of glucose tolerance. β-Cell function parameters were derived from established mathematical models yielding β-cell glucose sensitivity (βCGS), rate sensitivity, and insulin sensitivity in 255 obese adolescents (173 with normal glucose tolerance [NGT], 48 with impaired glucose tolerance [IGT], and 34 with type 2 diabetes [T2D]). The incretin effect was calculated as the ratio of the OGTT-βCGS to the 2-h hyperglycemic clamp-βCGS. Incretin and glucagon concentrations were measured during the OGTT. Compared with NGT, βCGS was 30 and 65% lower in youth with IGT and T2D, respectively; rate sensitivity was 40% lower in T2D. Youth with IGT or T2D had 32 and 38% reduced incretin effect compared with NGT in the face of similar changes in GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) in response to oral glucose. We conclude that glucose sensitivity deteriorates progressively in obese youth across the spectrum of glucose tolerance in association with impairment in incretin effect without reduction in GLP-1 or GIP, similar to that seen in adult dysglycemia.

To characterize the defects in β-cell function in subjects with impaired fasting glucose (IFG) and compare the results to impaired glucose tolerance (IGT) and normal glucose tolerance (NGT) subjects, β-cell glucose sensitivity and rate sensitivity during the oral glucose tolerance test were measured with the model by Mari in 172 Mexican Americans. A subgroup (n = 70) received a 2-h hyperglycemic clamp (+125 mg/dL), and first- and second-phase insulin secretion were quantitated. Compared with NGT, subjects with IFG and IGT manifested a decrease in β-cell glucose sensitivity; IFG subjects, but not IGT subjects, had decreased β-cell rate sensitivity. In IFG subjects, the defect in β-cell glucose sensitivity was time dependent, began to improve after 60 min, and was comparable to NGT after 90 min. The incremental area under the plasma C-peptide concentration curve during the first 12 min of the hyperglycemic clamp (ΔC-pep[AUC]0–12) was inversely related with the increase in FPG concentration (r = −36, r = 0.001), whereas ΔC-pep[AUC]15–120 positively correlated with FPG concentration (r = 0.29, r < 0.05). When adjusted for the prevailing level of insulin resistance, first-phase insulin secretion was markedly decreased in both IFG and IGT, whereas second-phase insulin secretion was decreased only in IGT. These results demonstrate distinct defects in β-cell function in IFG and IGT.

OBJECTIVE Recent work has shown that insulin stimulates its own secretion in insulin-sensitive humans, suggesting that insulin resistance in the β-cell could cause β-cell dysfunction. We have tested whether insulin exposure and insulin sensitivity modulate β-cell function in subjects with normal glucose tolerance (NGT) and whether they contribute to dysglycemia in impaired glucose regulation (IGR). RESEARCH DESIGN AND METHODS Insulin sensitivity (by euglycemic clamp), insulin-induced secretory response at isoglycemia (IISR) (as C-peptide percent change from basal during the clamp), glucose-induced secretory response (GISR) to an intravenous glucose bolus, and β-cell glucose sensitivity (β-GS) (by oral glucose tolerance test [OGTT] modeling) were measured in 1,151 NGT and 163 IGR subjects from the RISC (Relationship between Insulin Sensitivity and Cardiovascular Disease) study. RESULTS In NGT, IISR was related to both insulin sensitivity and antecedent insulin exposure; GISR was related to insulin exposure. IISR was positively, if weakly, related to β-GS (r= 0.16, P < 0.0001). Both IISR (−23 [39] vs. −9 [2]%, median [interquartile range], P < 0.03) and β-GS (69 [47] vs. 118 [83] pmol ⋅ min–1 ⋅ m–2 ⋅ mmol–1 ⋅ L, P < 0.0001) were decreased in IGR compared with NGT. Insulin sensitivity and β-GS were the major determinants of mean OGTT glucose in both NGT and IGR, with a minor role for IISR. In a multivariate logistic model, IGR was predicted by β-GS (odds ratio 4.84 [95% CI 2.89–8.09]) and insulin sensitivity (3.06 [2.19–4.27]) but not by IISR (1.11 [0.77–1.61]). CONCLUSIONS Pre-exposure to physiological hyperinsulinemia stimulates insulin secretion to a degree that depends on insulin sensitivity. However, this phenomenon has limited impact on β-cell dysfunction and dysglycemia.

OBJECTIVE Previous studies have found that high insulin sensitivity predicts weight gain; this association has not been confirmed. Our aim was to systematically analyze metabolic predictors of spontaneous weight changes. RESEARCH DESIGN AND METHODS In 561 women and 467 men from the Relationship Between Insulin Sensitivity and Cardiovascular Disease (RISC) cohort (mean age 44 years, BMI range 19–44 kg/m2, 9% impaired glucose tolerance) followed up for 3 years, we measured insulin sensitivity (by a euglycemic clamp) and β-cell function (by modeling of the C-peptide response to oral glucose and by acute insulin response to intravenous glucose). RESULTS Insulin sensitivity was similar in weight gainers (top 20% of the distribution of BMI changes), weight losers (bottom 20%), and weight stable subjects across quartiles of baseline BMI. By multiple logistic or linear regression analyses controlling for center, age, sex, and baseline BMI, neither insulin sensitivity nor any β-cell function parameter showed an independent association with weight gain; this was true in normal glucose tolerance, impaired glucose tolerance, and whether subjects progressed to dysglycemia or not. Baseline BMI was significantly higher in gainers (26.1 ± 4.1 kg/m2) and losers (26.6 ± 3.7 kg/m2) than in weight stable subjects (24.8 ± 3.8 kg/m2, P < 0.0001 for both gainers and losers). Baseline waist circumference (or equivalently, BMI or weight) was a positive, independent predictor of both weight gain and weight loss (odds ratio 1.48 [95% CI 1.12–1.97]) in men and (1.67 [1.28–2.12]) in women. In men only, better insulin sensitivity was an additional independent predictor of weight loss. CONCLUSIONS Neither insulin sensitivity nor insulin secretion predicts spontaneous weight gain. Individuals who have attained a higher weight are prone to either gaining or losing weight regardless of their glucose tolerance.

OBJECTIVE— Type 2 diabetes is characterized by impaired pancreatic β-cell function and decreased insulin sensitivity. Genome-wide association studies have identified common, novel type 2 diabetes susceptibility loci within the FTO, CDKAL1, CDKN2A/CDKN2B, IGF2BP2, HHEX/IDE, and SLC30A8 gene regions. Our objective was to explore the relationships between the diabetes-associated alleles and measures of β-cell function and whole-body insulin sensitivity.RESEARCH DESIGN AND METHODS— A total of 1,276 healthy subjects of European ancestry were studied at 19 centers. Indexes of β-cell function (including 30-min insulin response and glucose sensitivity) were derived from a 75-g oral glucose tolerance test, and whole-body insulin sensitivity (M/I) was assessed by hyperinsulinemic-euglycemic clamp. Genotype/phenotype relationships were studied by linear trend analysis correcting for age, sex, and recruitment center.RESULTS— CDKAL1 and HHEX/IDE diabetes-associated alleles were both associated with decreased 30-min insulin response (both P = 0.0002) and decreased pancreatic β-cell glucose sensitivity (P = 9.86 × 10−5 and 0.009, respectively), and these relationships remained after correction for M/I. The FTO susceptibility allele showed a weak but consistent association with increased adiposity, which in turn was linked to a decrease in M/I. However, none of the other novel diabetes susceptibility alleles were associated with insulin sensitivity.CONCLUSIONS— CDKAL1 and HHEX/IDE diabetes-associated alleles are associated with decreased pancreatic β-cell function, including decreased β-cell glucose sensitivity that relates insulin secretion to plasma glucose concentration. We confirmed the association between the FTO allele and increased adiposity, but none of the other novel susceptibility alleles were associated with whole-body insulin sensitivity.

Currently, there are no data in the literature regarding the pathophysiological mechanisms involved in the rapid resolution of type 2 diabetes after bariatric surgery, which was reported as an additional benefit of the surgical treatment for morbid obesity. With this question in mind, insulin sensitivity, using euglycemic-hyperinsulinemic clamp, and insulin secretion, by the C-peptide deconvolution method after an oral glucose load, together with the circulating levels of intestinal incretins and adipocytokines, have been studied in 10 diabetic morbidly obese subjects before and shortly after biliopancreatic diversion (BPD) to avoid the weight loss interference. Diabetes disappeared 1 week after BPD, while insulin sensitivity (32.96 ± 4.3 to 65.73 ± 3.22 μmol · kg fat-free mass−1 · min−1 at 1 week and to 64.73 ± 3.42 μmol · kg fat-free mass−1 · min−1 at 4 weeks; P < 0.0001) was fully normalized. Fasting insulin secretion rate (148.16 ± 20.07 to 70.0.2 ± 8.14 and 83.24 ± 8.28 pmol/min per m2; P < 0.01) and total insulin output (43.76 ± 4.07 to 25.48 ± 1.69 and 30.50 ± 4.71 nmol/m2; P < 0.05) dramatically decreased, while a significant improvement in β-cell glucose sensitivity was observed. Both fasting and glucose-stimulated gastrointestinal polypeptide (13.40 ± 1.99 to 6.58 ± 1.72 pmol/l at 1 week and 5.83 ± 0.80 pmol/l at 4 weeks) significantly (P < 0.001) decreased, while glucagon-like peptide 1 significantly increased (1.75 ± 0.16 to 3.42 ± 0.41 pmol/l at 1 week and 3.62 ± 0.21 pmol/l at 4 weeks; P < 0.001). BPD determines a prompt reversibility of type 2 diabetes by normalizing peripheral insulin sensitivity and enhancing β-cell sensitivity to glucose, these changes occurring very early after the operation. This operation may affect the enteroinsular axis function by diverting nutrients away from the proximal gastrointestinal tract and by delivering incompletely digested nutrients to the ileum.

Insulin hypersecretion and insulin resistance are physiologically linked features of obesity. We tested whether extreme hypersecretion impairs beta-cell function under free-living conditions and whether major weight loss modifies insulin hypersecretion, insulin sensitivity, and beta-cell function. Plasma glucose, C-peptide, and free fatty acid concentrations were measured at hourly intervals during 24 h of normal life (including calorie-standardized meals) in 20 morbidly obese nondiabetic patients (BMI 48.4 +/- 1.7 kg/m2) and 7 nonobese age- and sex-matched control subjects; 8 of the obese patients were restudied 6 months and 2 years following biliopancreatic diversion. Insulin secretion was reconstructed from C-peptide levels by deconvolution and related to concurrent glucose levels through a mathematical model incorporating key features of beta-cell function: rate sensitivity, beta-cell glucose sensitivity, and potentiation. Insulin sensitivity (by the euglycemic insulin clamp technique) was reduced by 50% in obese subjects (23.1 +/- 2.5 of obese subjects vs. 52.9 +/- 4.9 micromol.min(-1) . kg(FFM)(-1) of control subjects, means +/- SE, P = 0.0004) as was mean 24-h insulin clearance (median 809 [interquartile range 451] vs. 1,553 [520] ml.min(-1) . m(-2), P < 0.001) due to a 50% reduction in hepatic insulin extraction (P < 0.01). Over 24 h, insulin secretion was doubled in obese subjects (468 nmol [202] in obese subjects vs. 235 [85] of control subjects, P=0.0002). Despite the hypersecretion, beta-cell glucose sensitivity, rate sensitivity, and potentiation were similar in obese and control subjects. Six months postoperatively (weight loss = 33 +/- 3 kg), both insulin hypersecretion (282 nmol [213]) and insulin sensitivity (51.6 +/- 3.7 micromol.min(-1).kg(FFM)(-1)) were normalized. At 2 years (weight loss = 50 +/- 8 kg), insulin sensitivity was supernormal (68.7 +/- 3.3 micromol.min(-1).kg(FFM)(-1)) and insulin secretion was lower than normal (167 nmol [37]) (both P < 0.05 vs. control subjects). In conclusion, severe uncomplicated obesity is characterized by gross insulin hypersecretion and insulin resistance, but the dynamic aspects of beta-cell function are intact. Malabsorptive bariatric surgery corrects both the insulin hypersecretion and the insulin resistance at a time when BMI is still high. With continued weight loss over a 2-year period, moderately obese subjects become supersensitive to insulin and, correspondingly, insulin hyposecretors.

In nondiabetic subjects, obesity is associated with a modest expansion of β-cell mass, possibly amounting—according to the best available estimates—to 10–30% for each 10 kg of weight excess. Whether age of onset and duration of obesity, recent changes in body weight, and body fat distribution have any effect on β-cell mass in humans is unknown. Both fasting insulin secretion and the total insulin response to oral glucose have the following characteristics: 1) they increase with BMI in an approximately linear fashion, 2) both fat-free and fat mass are significant positive correlates, and 3) BMI exerts a positive effect separate from that of insulin resistance (i.e., obesity may be a state of primary insulin hypersecretion). The mechanisms are currently unknown, though chronic small increments in plasma glucose may play a role. In contrast, dynamic properties of β-cell function, such as glucose sensitivity (i.e., dose-response function), rate sensitivity, and potentiation, do not appear to be substantially altered by the presence of obesity, body fat distribution, or insulin resistance as long as glucose tolerance is maintained. Weight loss, by diet or restrictive bariatric surgery, is associated with consensual decrements in insulin resistance and insulin hypersecretion. The latter, however, seems to be more persistent, suggesting that the postobese state may reproduce the primary insulin hypersecretion of the obese state. Malabsorptive bariatric surgery, in contrast, normalizes insulin sensitivity and abolishes insulin hypersecretion even before achievement of ideal body weight. Lipid-triggered messages from the gastrointestinal tract to the insulin target tissues and endocrine pancreas are the subject of intense investigation.

First-phase insulin response to intravenous glucose is impaired both in type 2 diabetic patients and in subjects at risk for the disease. Hyperglycemia can modify β-cell response by either inhibiting or potentiating both first- and second-phase insulin release. In normal subjects, the effect of acute hyperglycemia on insulin secretion is controversial. We measured (in 13 healthy volunteers) insulin secretion (by deconvolution of plasma C-peptide concentrations) during three consecutive 30-min hyperglycemic steps (2.8, 2.8, and 5.6 mmol/l), followed by an intravenous arginine bolus. First-phase insulin secretion in response to the first hyperglycemic step (456 ± 83 pmol · min−1 · m−2) was significantly larger than that in response to the second step (311 ± 37 pmol · min−1 · m−2, P < 0.01); the subsequent increase in glycemia failed to stimulate first-phase secretion any further (377 ± 60 pmol · min−1 · m−2, NS vs. the previous value). This inhibition was also evident when insulin release rates were corrected for the respective increments (absolute or percentage) in plasma glucose levels and was not due to β-cell exhaustion because the arginine bolus still elicited a large peak of insulin secretion (4,790 ± 2,330 pmol · min−1 · m−2). In contrast, second-phase insulin secretion was related to the prevailing glucose levels across the three hyperglycemic steps in a direct quasilinear manner. We conclude that first-phase insulin secretion is inhibited by short-term modest hyperglycemia, whereas the second-phase insulin secretion increases linearly with hyperglycemia.

We developed a mathematical model of the glucose control of insulin secretion capable of quantifying β-cell function from a physiological meal test. The model includes a static control, i.e., a secretion component that is a function of plasma glucose concentration (the dose-response function), and a dynamic control, i.e., a secretion component that is proportional to the positive values of the glucose concentration derivative. Furthermore, the dose-response function is assumed to be modulated by a time-varying potentiation factor. To test the model, nine nondiabetic control subjects and nine type 2 diabetic patients received three standardized mixed meals over a period of 14–15 h. Blood samples were drawn for the measurement of glucose, insulin, and C-peptide concentration. The dose-response function, the parameter of the dynamic control, and the potentiation factor were determined by fitting the model to glucose and C-peptide concentrations. In diabetic patients, the dose-response function was shifted to the right (glucose concentration at a reference insulin secretion of 300 pmol · min−1 · m−2 was 11.7 ± 1.1 vs. 7.2 ± 0.7 mmol/l; P < 0.05), and decreased in slope (53 ± 15 vs. 148 ± 38 pmol · min−1 · m−2 · mmol−1 · l; P < 0.05) and the parameter of the dynamic control was decreased (220 ± 67 vs. 908 ± 276 pmol · m−2 · mmol−1 · l; P < 0.05) compared with the nondiabetic control subjects. Furthermore, potentiation was markedly blunted and delayed: maximum potentiation was observed at the first meal in normal subjects and at the second meal (about 4 h later) in diabetic subjects; the mean time for the potentiation factor was higher (7.1 ± 0.2 vs. 5.9 ± 0.2 h; P < 0.01), and the size of potentiation was reduced (2.6 ± 0.5 vs. 7.2 ± 1.5 fold increase; P < 0.005). In conclusion, our model of insulin secretion extracts multiple indexes of β-cell function from a physiological meal test. Use of the model in patients with type 2 diabetes retrieves known defects in insulin secretion but also uncovers new facets of β-cell dysfunction.

Hyperinsulinemia is a common finding in obesity and results from insulin hypersecretion and impaired hepatic insulin extraction. In vitro studies have shown that free fatty acids (FFAs), which are often elevated in obesity, can impair insulin binding and degradation in isolated rat hepatocytes. To investigate whether FFAs impair hepatic insulin extraction (E(H)) in vivo, either saline (SAL) or 10% Intralipid (0.03 ml x kg(-1) x min(-1)) plus heparin (0.44 U x kg(-1) x min(-1)) (IH) was infused into normal dogs to elevate FFA levels. Insulin was infused intraportally at 18 pmol x kg(-1) x min(-1) for 150 min (period A, high insulin dose), and then at 2.4 pmol x kg(-1) x min(-1) for another 150 min (period B, low insulin dose). After the low portal insulin dose, additional insulin was infused peripherally at 8.4 pmol x kg(-1) x min(-1) for 120 min (period C) to assess the clearance of insulin from the peripheral plasma. In 16 paired experiments, FFA levels were 1,085 +/- 167, 1,491 +/- 240, 1,159 +/- 221 micromol/l (IH) and 221 +/- 44, 329 +/- 72, 176 +/- 44 micromol/l (SAL) in periods A, B, and C, respectively. Peripheral insulin levels were greater with IH (P < 0.001) than with SAL in all periods (1,620 +/- 114, 126 +/- 12, 1,050 +/- 72 pmol/l for IH vs. 1,344 +/- 168, 96 +/- 4.2, 882 +/- 60 pmol/l for SAL). Glucose clearance was impaired by IH in all periods (P < 0.05), whereas glucose production was slightly increased by IH during period B. Peripheral insulin clearance (Cl) and E(H) were calculated from the insulin infusion rate and insulin concentration data in each period by taking into account the nonlinearity of insulin kinetics. Cl was lower (P < 0.01) with IH (9.6 +/- 0.6, 12.0 +/- 0.9, 10.2 +/- 0.6 ml x kg(-1) x min(-1)) than with SAL (11.2 +/- 1, 13.6 +/- 0.7, 11.9 +/- 0.9 ml x kg(-1) x min(-1)) in periods A, B, and C. E(H) was also lower (P < 0.05) with IH (25 +/- 4, 40 +/- 5, 32 +/- 5%) than with SAL (30 +/- 2.8, 47 +/- 3, 38 +/- 3%). We conclude that FFAs can impair hepatic insulin extraction in vivo at high and low insulin levels, an effect that may contribute to the peripheral hyperinsulinemia of obesity.

OBJECTIVE Recent work has shown that insulin stimulates its own secretion in insulin-sensitive humans, suggesting that insulin resistance in the β-cell could cause β-cell dysfunction. We have tested whether insulin exposure and insulin sensitivity modulate β-cell function in subjects with normal glucose tolerance (NGT) and whether they contribute to dysglycemia in impaired glucose regulation (IGR). RESEARCH DESIGN AND METHODS Insulin sensitivity (by euglycemic clamp), insulin-induced secretory response at isoglycemia (IISR) (as C-peptide percent change from basal during the clamp), glucose-induced secretory response (GISR) to an intravenous glucose bolus, and β-cell glucose sensitivity (β-GS) (by oral glucose tolerance test [OGTT] modeling) were measured in 1,151 NGT and 163 IGR subjects from the RISC (Relationship between Insulin Sensitivity and Cardiovascular Disease) study. RESULTS In NGT, IISR was related to both insulin sensitivity and antecedent insulin exposure; GISR was related to insulin exposure. IISR was positively, if weakly, related to β-GS (r= 0.16, P < 0.0001). Both IISR (−23 [39] vs. −9 [2]%, median [interquartile range], P < 0.03) and β-GS (69 [47] vs. 118 [83] pmol ⋅ min–1 ⋅ m–2 ⋅ mmol–1 ⋅ L, P < 0.0001) were decreased in IGR compared with NGT. Insulin sensitivity and β-GS were the major determinants of mean OGTT glucose in both NGT and IGR, with a minor role for IISR. In a multivariate logistic model, IGR was predicted by β-GS (odds ratio 4.84 [95% CI 2.89–8.09]) and insulin sensitivity (3.06 [2.19–4.27]) but not by IISR (1.11 [0.77–1.61]). CONCLUSIONS Pre-exposure to physiological hyperinsulinemia stimulates insulin secretion to a degree that depends on insulin sensitivity. However, this phenomenon has limited impact on β-cell dysfunction and dysglycemia.

OBJECTIVE Previous studies have found that high insulin sensitivity predicts weight gain; this association has not been confirmed. Our aim was to systematically analyze metabolic predictors of spontaneous weight changes. RESEARCH DESIGN AND METHODS In 561 women and 467 men from the Relationship Between Insulin Sensitivity and Cardiovascular Disease (RISC) cohort (mean age 44 years, BMI range 19–44 kg/m2, 9% impaired glucose tolerance) followed up for 3 years, we measured insulin sensitivity (by a euglycemic clamp) and β-cell function (by modeling of the C-peptide response to oral glucose and by acute insulin response to intravenous glucose). RESULTS Insulin sensitivity was similar in weight gainers (top 20% of the distribution of BMI changes), weight losers (bottom 20%), and weight stable subjects across quartiles of baseline BMI. By multiple logistic or linear regression analyses controlling for center, age, sex, and baseline BMI, neither insulin sensitivity nor any β-cell function parameter showed an independent association with weight gain; this was true in normal glucose tolerance, impaired glucose tolerance, and whether subjects progressed to dysglycemia or not. Baseline BMI was significantly higher in gainers (26.1 ± 4.1 kg/m2) and losers (26.6 ± 3.7 kg/m2) than in weight stable subjects (24.8 ± 3.8 kg/m2, P < 0.0001 for both gainers and losers). Baseline waist circumference (or equivalently, BMI or weight) was a positive, independent predictor of both weight gain and weight loss (odds ratio 1.48 [95% CI 1.12–1.97]) in men and (1.67 [1.28–2.12]) in women. In men only, better insulin sensitivity was an additional independent predictor of weight loss. CONCLUSIONS Neither insulin sensitivity nor insulin secretion predicts spontaneous weight gain. Individuals who have attained a higher weight are prone to either gaining or losing weight regardless of their glucose tolerance.

We developed a mathematical model of the glucose control of insulin secretion capable of quantifying beta-cell function from a physiological meal test. The model includes a static control, i.e., a secretion component that is a function of plasma glucose concentration (the dose-response function), and a dynamic control, i.e., a secretion component that is proportional to the positive values of the glucose concentration derivative. Furthermore, the dose-response function is assumed to be modulated by a time-varying potentiation factor. To test the model, nine nondiabetic control subjects and nine type 2 diabetic patients received three standardized mixed meals over a period of 14-15 h. Blood samples were drawn for the measurement of glucose, insulin, and C-peptide concentration. The dose-response function, the parameter of the dynamic control, and the potentiation factor were determined by fitting the model to glucose and C-peptide concentrations. In diabetic patients, the dose-response function was shifted to the right (glucose concentration at a reference insulin secretion of 300 pmol.min(-1).m(-2) was 11.7 +/- 1.1 vs. 7.2 +/- 0.7 mmol/l; P0.05), and decreased in slope (53 +/- 15 vs. 148 +/- 38 pmol.min(-1).m(-2).mmol(-1).l; P0.05) and the parameter of the dynamic control was decreased (220 +/- 67 vs. 908 +/- 276 pmol.m(-2).mmol(-1).l; P0.05) compared with the nondiabetic control subjects. Furthermore, potentiation was markedly blunted and delayed: maximum potentiation was observed at the first meal in normal subjects and at the second meal (about 4 h later) in diabetic subjects; the mean time for the potentiation factor was higher (7.1 +/- 0.2 vs. 5.9 +/- 0.2 h; P0.01), and the size of potentiation was reduced (2.6 +/- 0.5 vs. 7.2 +/- 1.5 fold increase; P0.005). In conclusion, our model of insulin secretion extracts multiple indexes of beta-cell function from a physiological meal test. Use of the model in patients with type 2 diabetes retrieves known defects in insulin secretion but also uncovers new facets of beta-cell dysfunction.