Gastrointestinal tolerability of once-weekly semaglutide 2.4 mg in adults with overweight or obesity, and the relationship between gastrointestinal adverse events and weight loss.

AIM: We evaluated gastrointestinal (GI) adverse events (AEs) with once-weekly semaglutide 2.4 mg in adults with overweight or obesity and their contribution to weight loss (WL). MATERIALS AND METHODS: AE analyses pooled data from the Semaglutide Treatment Effect in People With Obesity (STEP) 1-3 trials for participants randomized to 68 weeks of semaglutide 2.4 mg (n = 2117) or placebo (n = 1262). WL was analysed by presence/absence of GI AEs. Mediation analysis estimated WL effects mediated by and unrelated to GI AEs. GI tolerability with semaglutide 2.4 mg maintenance and cessation after dose escalation was evaluated using STEP 4 data among 803 participants tolerating 20 weeks of semaglutide run-in. RESULTS: GI AEs were more common with semaglutide 2.4 mg than placebo, with most frequently nausea (43.9% vs. 16.1% of participants), diarrhoea (29.7% vs. 15.9%), vomiting (24.5% vs. 6.3%) and constipation (24.2% vs. 11.1%). Most GI AEs with semaglutide were non-serious (99.5% of AEs), mild-to-moderate (98.1%), transient and occurred most frequently during/shortly after dose escalation. Few semaglutide-treated participants (4.3%) permanently discontinued treatment for GI AEs. In STEP 1-3, mean WL with semaglutide 2.4 mg was similar in participants without (9.6%-17.1%) versus with GI AEs (11.4%-17.7%). Consistent with this observation, mediation analysis found that GI AEs contributed little to semaglutide-induced WL: of the additional 7.6%-14.4% WL with semaglutide versus placebo, <1 percentage point was mediated by GI AEs. In STEP 4, semaglutide 2.4 mg maintenance was well tolerated. CONCLUSIONS: GI AEs were more common with semaglutide 2.4 mg than placebo, but typically mild-to-moderate and transient. Semaglutide-induced WL was largely independent of GI AEs.

Glucose-dependent insulinotropic polypeptide induces lipolysis during stable basal insulin substitution and hyperglycaemia in men with type 1 diabetes: A randomized, double-blind, placebo-controlled, crossover clinical trial.

Glucose-dependent insulinotropic polypeptide (GIP) plays an important role in the glucose and lipid metabolism. We investigated the effects of exogenous GIP on lipid metabolism during time of stable insulin levels. Ten male patients with type 1 diabetes without endogenous insulin secretion (C-peptide-negative, mean [±SD] age 26 ± 4years, body mass index 24 [±2] kg/m2 , glycated haemoglobin 56 [±8] mmol/mol or 7.3 [±0.8]%) were studied in a randomized, double-blind, placebo-controlled, crossover study with continuous intravenous infusions of GIP (4 pmol/kg/min) or placebo (saline), during two separate 90-minute hyperglycaemic (12 mmol/L) clamps with basal insulin substitution (0.1-0.2 mU/kg/min). Plasma glycerol concentrations increased from baseline during GIP infusion and decreased during placebo infusion (baseline-subtracted area under the curve [bsAUC] 703 ± 407 vs. -262 ± 240 µmol/L × min, respectively; P < 0.001). Free fatty acids (FFAs) increased during GIP infusions (bsAUC 5505 ± 2170 µEq/L × min) and remained unchanged during placebo infusion (bsAUC -74 ± 2363 µEq/L × min), resulting in a significant difference between GIP and placebo infusions (P < 0.001). Plasma concentrations of glucose, insulin, glucagon-like peptide-1 and glucagon were similar during GIP and placebo infusions. GIP increased plasma glycerol and FFAs in patients with type 1 diabetes during hyperglycaemia and stable basal insulin levels. This supports a direct lipolytic effect of GIP at high glucose and low levels of plasma insulin.

Once-Weekly Semaglutide in Adults with Overweight or Obesity.

BACKGROUND: Obesity is a global health challenge with few pharmacologic options. Whether adults with obesity can achieve weight loss with once-weekly semaglutide at a dose of 2.4 mg as an adjunct to lifestyle intervention has not been confirmed. METHODS: In this double-blind trial, we enrolled 1961 adults with a body-mass index (the weight in kilograms divided by the square of the height in meters) of 30 or greater (≥27 in persons with ≥1 weight-related coexisting condition), who did not have diabetes, and randomly assigned them, in a 2:1 ratio, to 68 weeks of treatment with once-weekly subcutaneous semaglutide (at a dose of 2.4 mg) or placebo, plus lifestyle intervention. The coprimary end points were the percentage change in body weight and weight reduction of at least 5%. The primary estimand (a precise description of the treatment effect reflecting the objective of the clinical trial) assessed effects regardless of treatment discontinuation or rescue interventions. RESULTS: The mean change in body weight from baseline to week 68 was -14.9% in the semaglutide group as compared with -2.4% with placebo, for an estimated treatment difference of -12.4 percentage points (95% confidence interval [CI], -13.4 to -11.5; P<0.001). More participants in the semaglutide group than in the placebo group achieved weight reductions of 5% or more (1047 participants [86.4%] vs. 182 [31.5%]), 10% or more (838 [69.1%] vs. 69 [12.0%]), and 15% or more (612 [50.5%] vs. 28 [4.9%]) at week 68 (P<0.001 for all three comparisons of odds). The change in body weight from baseline to week 68 was -15.3 kg in the semaglutide group as compared with -2.6 kg in the placebo group (estimated treatment difference, -12.7 kg; 95% CI, -13.7 to -11.7). Participants who received semaglutide had a greater improvement with respect to cardiometabolic risk factors and a greater increase in participant-reported physical functioning from baseline than those who received placebo. Nausea and diarrhea were the most common adverse events with semaglutide; they were typically transient and mild-to-moderate in severity and subsided with time. More participants in the semaglutide group than in the placebo group discontinued treatment owing to gastrointestinal events (59 [4.5%] vs. 5 [0.8%]). CONCLUSIONS: In participants with overweight or obesity, 2.4 mg of semaglutide once weekly plus lifestyle intervention was associated with sustained, clinically relevant reduction in body weight. (Funded by Novo Nordisk; STEP 1 ClinicalTrials.gov number, NCT03548935).

Semaglutide for the treatment of non-alcoholic steatohepatitis: Trial design and comparison of non-invasive biomarkers.

Non-alcoholic steatohepatitis (NASH) is a chronic liver disease. There is a clear need to develop pharmacological treatment for patients with NASH as well as biomarkers that can diagnose the disease. We describe a trial of semaglutide treatment for NASH, identify key patient characteristics and compare the relationship of patient characteristics and non-invasive biomarkers/scores. NCT02970942 is a randomised, double-blind, placebo-controlled, multi-national Phase 2 trial of daily subcutaneous semaglutide (0.1 mg, 0.2 mg, 0.4 mg) in patients with biopsy-confirmed NASH, F1-F3 fibrosis, NAFLD Activity Score ≥ 4, and body mass index (BMI) > 25 kg/m2. Exploratory analyses were performed to evaluate correlations between baseline parameters and biomarkers in NASH. Mean (standard deviation [SD]) age of 320 randomised patients was 55 (11) years, mean BMI was 36 (6) kg/m2, and 199 (62%) had type 2 diabetes. Of the total patients, 28% had F1 fibrosis, 23% had F2 fibrosis and 49% had F3 fibrosis. The highest area under the receiver operating characteristic curve (0.69) for accuracy in classifying fibrosis stage, F2-3 versus F1, was observed for Fib-4 and Enhanced Liver Fibrosis (ELF). No substantial correlation between BMI or other clinical or biochemical parameters and fibrosis stage was observed. In this large Phase 2 trial of semaglutide treatment for NASH, the clinical profile of enrolled patients was typical for patients with NASH. Of the investigated biomarkers/scores, ELF and Fib-4 showed the most apparent correlation in classifying fibrosis stage, but had only moderate predictive value.

Semaglutide 2.4 mg for the Treatment of Obesity: Key Elements of the STEP Trials 1 to 5.

OBJECTIVE: The obesity epidemic is a public health concern, warranting further research into pharmacological treatments for weight management (WM) as an adjunct to lifestyle interventions. The Semaglutide Treatment Effect in People with obesity (STEP) program aims to investigate the effect of semaglutide versus placebo on weight loss, safety, and tolerability in adults with obesity or overweight. METHODS: Across five phase 3 trials (NCT03548935, WM; NCT03552757, WM in type 2 diabetes; NCT03611582, WM with intensive behavioral therapy; NCT03548987, sustained WM; and NCT03693430, long-term WM), ~5,000 participants are being randomly assigned to receive semaglutide 2.4 mg once weekly subcutaneously versus placebo. Results will be available in 2020/2021. For all trials, the primary end point is change from baseline to end of treatment in body weight. RESULTS: Participants have a mean age of 46.2 to 55.3 years, are mostly female (mean: 74.1%-81.0%), and have a mean BMI of 35.7 to 38.5 kg/m2 and a mean waist circumference of 113.0 to 115.7 cm. CONCLUSIONS: The STEP program evaluates the efficacy and safety of semaglutide 2.4 mg subcutaneously once weekly in a broad population. The trials will provide insights on WM in people with obesity with and without type 2 diabetes and on long-term follow-up.

Effect of semaglutide on liver enzymes and markers of inflammation in subjects with type 2 diabetes and/or obesity.

BACKGROUND: Obesity and type 2 diabetes are drivers of non-alcoholic fatty liver disease (NAFLD). Glucagon-like peptide-1 analogues effectively treat obesity and type 2 diabetes and may offer potential for NAFLD treatment. AIM: To evaluate the effect of the glucagon-like peptide-1 analogue, semaglutide, on alanine aminotransferase (ALT) and high-sensitivity C-reactive protein (hsCRP) in subjects at risk of NAFLD. METHODS: Data from a 104-week cardiovascular outcomes trial in type 2 diabetes (semaglutide 0.5 or 1.0 mg/week) and a 52-week weight management trial (semaglutide 0.05-0.4 mg/day) were analysed. Treatment ratios vs placebo were estimated for ALT (both trials) and hsCRP (weight management trial only) using a mixed model for repeated measurements, with or without adjustment for change in body weight. RESULTS: Elevated baseline ALT (men >30 IU/L; women >19 IU/L) was present in 52% (499/957) of weight management trial subjects. In this group with elevated ALT, end-of-treatment ALT reductions were 6%-21% (P<0.05 for doses≥0.2 mg/day) and hsCRP reductions 25%-43% vs placebo (P < 0.05 for 0.2 and 0.4 mg/day). Normalisation of elevated baseline ALT occurred in 25%-46% of weight management trial subjects, vs 18% on placebo. Elevated baseline ALT was present in 41% (1325/3268) of cardiovascular outcomes trial subjects. In this group with elevated ALT, no significant ALT reduction was noted at end-of-treatment for 0.5 mg/week, while a 9% reduction vs placebo was seen for 1.0 mg/week (P = 0.0024). Treatment ratios for changes in ALT and hsCRP were not statistically significant after adjustment for weight change. CONCLUSIONS: Semaglutide significantly reduced ALT and hsCRP in clinical trials in subjects with obesity and/or type 2 diabetes.

Neoplasms Reported With Liraglutide or Placebo in People With Type 2 Diabetes: Results From the LEADER Randomized Trial.

OBJECTIVE: This study explored neoplasm risk with liraglutide versus placebo in the LEADER (Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Outcome Results) cohort. RESEARCH DESIGN AND METHODS: LEADER (NCT01179048) was an international, phase 3b, randomized, double-blind, controlled trial. Participants aged ≥50 years with type 2 diabetes and high cardiovascular risk were assigned 1:1 to receive liraglutide (≤1.8 mg daily; n = 4,668) or placebo (n = 4,672) in addition to standard care and monitored for 3.5-5 years (median follow-up 3.8 years). The occurrence of neoplasms was a prespecified, exploratory secondary end point. Post hoc analyses of the time to the first confirmed neoplasms were conducted using a Cox regression model. RESULTS: Neoplasm was confirmed in 10.1% of patients with liraglutide versus 9.0% with placebo (hazard ratio [HR] 1.12 [95% CI 0.99; 1.28]). The HR (95% CI) for liraglutide versus placebo was 1.06 (0.90; 1.25) for malignant neoplasms and 1.16 (0.93; 1.44) for benign neoplasms. Sensitivity analyses excluding neoplasms occurring <1 year or <2 years after randomization and analyses by sex provided similar results. In our main analyses, the 95% CI for the HR included one for all malignant neoplasms evaluated (including pancreatic and thyroid neoplasms) except for prostate neoplasms, which occurred in fewer liraglutide-treated patients. CONCLUSIONS: LEADER was not primarily designed to assess neoplasm risk. Firm conclusions cannot be made regarding numeric imbalances observed for individual neoplasm types (e.g., pancreatic cancer) that occurred infrequently. LEADER data do, however, exclude a major increase in the risk of total malignant neoplasms with liraglutide versus placebo. Additional studies are needed to assess longer-term exposure.

Hypoglycemia, Cardiovascular Outcomes, and Death: The LEADER Experience.

OBJECTIVE: In the Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Outcome Results (LEADER) cardiovascular (CV) outcomes trial (NCT01179048), liraglutide significantly reduced the risk of CV events (by 13%) and hypoglycemia versus placebo. This post hoc analysis examines the associations between hypoglycemia and CV outcomes and death. RESEARCH DESIGN AND METHODS: Patients with type 2 diabetes and high risk for CV disease (n = 9,340) were randomized 1:1 to liraglutide or placebo, both in addition to standard treatment, and followed for 3.5-5 years. The primary end point was time to first major adverse cardiovascular event (MACE) (1,302 first events recorded), and secondary end points included incidence of hypoglycemia. We used Cox regression to analyze time to first MACE, CV death, non-CV death, or all-cause death with hypoglycemia as a factor or time-dependent covariate. RESULTS: A total of 267 patients experienced severe hypoglycemia (liraglutide n = 114, placebo n = 153; rate ratio 0.69; 95% CI 0.51, 0.93). These patients had longer diabetes duration, higher incidence of heart failure and kidney disease, and used insulin more frequently at baseline than those without severe hypoglycemia. In combined analysis (liraglutide and placebo), patients with severe hypoglycemia were more likely to experience MACE, CV death, and all-cause death, with higher risk shortly after hypoglycemia. The impact of liraglutide on risk of MACE was similar in patients with and without severe hypoglycemia (P-interaction = 0.90). CONCLUSIONS: Patients experiencing severe hypoglycemia were at greater risk of CV events and death, particularly shortly after the hypoglycemic episode. While causality remains unclear, reducing hypoglycemia remains an important goal in diabetes management.

Glucose-Dependent Insulinotropic Polypeptide (GIP) Inhibits Bone Resorption Independently of Insulin and Glycemia.

Context: The gut hormone glucose-dependent insulinotropic polypeptide (GIP) causes postprandial insulin release and inhibits bone resorption assessed by carboxy-terminal collagen crosslinks (CTX). Objective: To study if GIP affects bone homeostasis biomarkers independently of insulin release and glycemic level. Design: Randomized, double-blinded, crossover study with 5 study days. Patients: Ten male C-peptide-negative patients with type 1 diabetes. Interventions: On 3 matched days with "low glycemia" (plasma glucose in the interval 3 to 7 mmol/L for 120 minutes), we administered intravenous (IV) GIP (4 pmol × kg-1 × min-1), glucagon-like peptide 1 (1 pmol × kg-1 × min-1), or placebo (saline), and on 2 matched days with "high glycemia" (plasma glucose 12 mmol/L for 90 minutes), we administered either GIP or saline. Main Outcome Measures: CTX, procollagen type 1 N-terminal propeptide (P1NP), and parathyroid hormone (PTH). Results: During low glycemia: GIP progressively suppressed CTX from baseline by up to 59 ± 18% compared with 24 ± 10% during saline infusion (P < 0.0001). Absolute values of P1NP and PTH did not differ between days. During high glycemia: GIP suppressed CTX from baseline by up to 59 ± 19% compared with 7 ± 9% during saline infusion (P < 0.0001). P1NP did not differ between days. GIP suppressed PTH after 60 minutes compared with saline (P < 0.01), but this difference disappeared after 90 minutes. Conclusions: Short-term GIP infusions robustly reduce bone resorption independently of endogenous insulin secretion and during both elevated and low plasma glucose, but have no effect on P1NP or PTH after 90 minutes.

Hepatic insulin resistance in NAFLD: relationship with markers of atherosclerosis and metabolic syndrome components.

AIMS: Fat accumulation in the liver and in the muscle results in hepatic and muscle insulin resistance and has been associated with increased cardiovascular risk. It is unclear whether the individual role of hepatic and muscle insulin resistance in the onset of dyslipidaemia is observed in nonalcoholic fatty liver disease (NAFLD) patients and whether this association is mediated through traditional risk factors. The aim of this study was to assess hepatic and muscle insulin resistance in NAFLD and its relationship with carotid artery intima-media thickness (IMT) and the apoB/apoAI ratio as markers of atherosclerosis. METHODS: We studied 132 patients with a non-invasive diagnosis of NAFLD stratified into two groups according to the severity of steatosis at ultrasound scan. In all subjects, we measured hepatic insulin resistance (H-IR) and muscle insulin sensitivity index (MISI) by oral glucose tolerance test as proposed by DeFronzo, IMT, apoB/apoAI and the components of the metabolic syndrome (MS) as defined by ATP III. RESULTS: H-IR was significantly higher in moderate/severe steatosis than in the mild steatosis group (p < 0.0001). By contrast, MISI did not differ between the two groups. There was a significant correlation between H-IR, MISI and all of the components of MS. H-IR was significantly correlated with carotid IMT (r = 0.35; p < 0.0001) and the apoB/apoAI ratio (r = 0.43; p < 0.0001). Otherwise, a significant correlation was observed only between MISI and apoB/apoAI ratio. Multivariate analysis revealed that H-IR is related to early markers of atherosclerosis independent of MS components. CONCLUSIONS: In our study population, NAFLD was positively associated with carotid IMT, and this association is independent of MS components, but strictly related to H-IR that might contribute to the development of atherosclerosis through an impairment of the lipid profile in terms of the apoB/apoAI ratio. By contrast, no significant relation was observed between MISI and carotid IMT.

Glucose-dependent insulinotropic polypeptide augments glucagon responses to hypoglycemia in type 1 diabetes.

Glucose-dependent insulinotropic polypeptide (GIP) is glucagonotropic, and glucagon-like peptide-1 (GLP-1) is glucagonostatic. We studied the effects of GIP and GLP-1 on glucagon responses to insulin-induced hypoglycemia in patients with type 1 diabetes mellitus (T1DM). Ten male subjects with T1DM (C-peptide negative, age [mean ± SEM] 26 ± 1 years, BMI 24 ± 0.5 kg/m(2), HbA1c 7.3 ± 0.2%) were studied in a randomized, double-blinded, crossover study, with 2-h intravenous administration of saline, GIP, or GLP-1. The first hour, plasma glucose was lowered by insulin infusion, and the second hour constituted a "recovery phase." During the recovery phase, GIP infusions elicited larger glucagon responses (164 ± 50 [GIP] vs. 23 ± 25 [GLP-1] vs. 17 ± 46 [saline] min ⋅ pmol/L, P < 0.03) and endogenous glucose production was higher with GIP and lower with GLP-1 compared with saline (P < 0.02). On the GIP days, significantly less exogenous glucose was needed to keep plasma glucose above 2 mmol/L (155 ± 36 [GIP] vs. 232 ± 40 [GLP-1] vs. 212 ± 56 [saline] mg ⋅ kg(-1), P < 0.05). Levels of insulin, cortisol, growth hormone, and noradrenaline, as well as hypoglycemic symptoms and cognitive function, were similar on all days. Our results suggest that during hypoglycemia in patients with T1DM, exogenous GIP increases glucagon responses during the recovery phase after hypoglycemia and reduces the need for glucose administration.

Chronic exposure to GLP-1 increases GLP-1 synthesis and release in a pancreatic alpha cell line (α-TC1): evidence of a direct effect of GLP-1 on pancreatic alpha cells.

AIMS/HYPOTHESIS: Incretin therapies, which are used to treat diabetic patients, cause a chronic supra-physiological increase in GLP-1 circulating levels. It is still unclear how the resulting high hormone concentrations may affect pancreatic alpha cells. The present study was designed to investigate the effects of chronic exposure to high GLP-1 levels on a cultured pancreatic alpha cell line. METHODS: α-TC1-6 cell line was cultured in the presence or absence of GLP-1 (100 nmol/l) for up to 72 h. In our model GLP-1 receptor (GLP-1R) was measured. After the cells were exposed to GLP-1 the levels of glucagon secretion were measured. Because GLP-1 acts on intracellular cAMP production, the function of GLP-1R was studied. We also investigated the effects of chronic GLP-1 exposure on the cAMP/MAPK pathway, Pax6 levels, the expression of prohormone convertases (PCs), glucagon gene (Gcg) and protein expression, glucagon and GLP-1 production. RESULTS: In our model, we were able to detect GLP-1R. After GLP-1 exposure we found a reduction in glucagon secretion. During further investigation of the function of GLP-1R, we found an activation of the cAMP/MAPK/Pax6 pathway and an increase of Gcg gene and protein expression. Furthermore we observed a significant increase in PC1/3 protein expression, GLP-1 intracellular content and GLP-1 secretion. CONCLUSIONS/INTERPRETATION: Our data indicate that the chronic exposure of pancreatic alpha cells to GLP-1 increases the ability of these cells to produce and release GLP-1. This phenomenon occurs through the stimulation of the transcription factor Pax6 and the increased expression of the protein convertase PC1/3.

Cardiovascular risk profile in subjects with prediabetes and new-onset type 2 diabetes identified by HbA(1c) according to American Diabetes Association criteria.

OBJECTIVE: We investigated the cardiovascular risk profile in subjects with prediabetes and new-onset type 2 diabetes identified by glycated hemoglobin A1c (HbA(1c)) according to the new American Diabetes Association criteria. RESEARCH DESIGN AND METHODS: Arterial stiffness, intima-media thickness (IMT), soluble receptor for advanced glycation end products (sRAGEs), and oral glucose tolerance test (OGTT) were evaluated in 274 subjects without a previous history of diabetes. The subjects were stratified into three groups according to the HbA(1c) levels. RESULTS: The subjects with prediabetes (n = 117, HbA(1c) 5.7-6.4% [39-46 mmol/mol]) showed a higher augmentation (Aug), augmentation index (AugI), and IMT compared with those with lower HbA1c; however, these values were similar to those of subjects with HbA(1c) >6.5% (48 mmol/mol). When we further analyzed the subjects with prediabetes but included only subjects with normal glucose tolerance (NT) in the analysis, AugI and IMT still remained significantly higher than their levels in control subjects with HbA(1c) <5.7% (39 mmol/mol). After multiple regression analyses including several cardiovascular risk factors, only HbA(1c), age, and sRAGE were significantly correlated with the IMT, whereas age and 1-h postload glucose were the major determinants of AugI. CONCLUSIONS: Our data show that subjects with prediabetes according to HbA1c, but with both NT according to the OGTT and normal fasting glycemia, have an altered IMT and AugI. These data suggest that a simple, reproducible, and less expensive marker such as HbA1c may be better able to identify prediabetic subjects at high cardiovascular risk compared with fasting glycemia or OGTT alone.

Glucose-dependent insulinotropic polypeptide: blood glucose stabilizing effects in patients with type 2 diabetes.

CONTEXT: Patients with type 2 diabetes mellitus (T2DM) have clinically relevant disturbances in the effects of the hormone glucose-dependent insulinotropic polypeptide (GIP). OBJECTIVE: We aimed to evaluate the importance of the prevailing plasma glucose levels for the effect of GIP on responses of glucagon and insulin and glucose disposal in patients with T2DM. DESIGN AND SETTING: We performed a single center, placebo-controlled, cross-over, experimental study. PATIENTS: We studied twelve patients with T2DM (age: 62 ± 1 years [mean ± SEM], body mass index: 29 ± 1 kg/m(2); glycosylated hemoglobin A1c: 6.5 ± 0.1% [48 ± 2 mmol/mol]). INTERVENTION: We infused physiological amounts of GIP (2 pmol × kg(-1) × min(-1)) or saline. MAIN OUTCOME MEASURES: We measured plasma concentrations of glucagon, glucose, insulin, C-peptide, intact GIP, and amounts of glucose needed to maintain glucose clamps. RESULTS: During fasting glycemia (plasma glucose ∼8 mmol/L), GIP elicited significant increments in both insulin and glucagon levels, resulting in neutral effects on plasma glucose. During insulin-induced hypoglycemia (plasma glucose ∼3 mmol/L), GIP elicited a minor early-phase insulin response and increased glucagon levels during the initial 30 minutes, resulting in less glucose needed to be infused to maintain the clamp (29 ± 8 vs 49 ± 12 mg × kg(-1), P < .03). During hyperglycemia (1.5 × fasting plasma glucose ∼12 mmol/L), GIP augmented insulin secretion throughout the clamp, with slightly less glucagon suppression compared with saline, resulting in more glucose needed to maintain the clamp during GIP infusions (265 ± 21 vs 213 ± 13 mg × kg(-1), P < .001). CONCLUSIONS: In patients with T2DM, GIP counteracts insulin-induced hypoglycemia, most likely through a predominant glucagonotropic effect. In contrast, during hyperglycemia, GIP increases glucose disposal through a predominant effect on insulin release.

Alpha- and beta-cell abnormalities in haemoglobin A1c-defined prediabetes and type 2 diabetes.

New recommendations for the use of glycated haemoglobin A1c (HbA1c) to diagnose prediabetes and type 2 diabetes have changed the constitution of the two populations. We aimed to investigate the pathophysiological characteristics of individuals with HbA1c-defined prediabetes and type 2 diabetes, respectively. Ten subjects with HbA1c-defined prediabetes, i.e. HbA1c from 5.7 to 6.4 % (39-46 mmol/mol), eight newly diagnosed patients with HbA1c-defined type 2 diabetes [HbA1c ≥6.5 % (≥48 mmol/mol)], and ten controls with HbA1c lower than 5.7 % (<39 mmol/mol), were studied. Blood was sampled over 4 h on two separate days after a 75 g-oral glucose tolerance test and an isoglycaemic intravenous glucose infusion, respectively. Blood was analysed for glucose, insulin, C-peptide, glucagon, and incretin hormones. Insulinogenic index, disposition index, glucagon suppression, and incretin effect were evaluated. Subjects with HbA1c-defined prediabetes showed significantly lower insulinogenic index (P = 0.02), disposition index (P = 0.001), and glucagon suppression compared with controls; and similar (P = NS) insulinogenic index and glucagon suppression and higher disposition index (P = 0.02) compared to HbA1c-diagnosed type 2 diabetic patients. The patients with type 2 diabetes showed lower insulinogenic index (P = 0.0003), disposition index (P < 0.0001), and glucagon suppression compared with the controls. The incretin effect was significantly (P < 0.05) reduced in patients with HbA1c-defined type 2 diabetes compared to subjects with HbA1c-defined prediabetes and controls. Plasma levels of incretin hormones were similar across the three groups. HbA1c associated negatively with insulinogenic index, disposition index, and incretin effect. Our findings show clear alpha- and beta-cell dysfunction in HbA1c-defined type 2 diabetes compatible with the previously described pathophysiology of plasma glucose-defined type 2 diabetes. Furthermore, in HbA1c-defined prediabetes, we show defective insulin response in combination with inappropriate suppression of glucagon, which may constitute new targets for pharmacological interventions.

Secretion of glucose-dependent insulinotropic polypeptide in patients with type 2 diabetes: systematic review and meta-analysis of clinical studies.

OBJECTIVE: To investigate glucose-dependent insulinotropic polypeptide (GIP) secretion in patients with type 2 diabetes and nondiabetic control subjects during oral glucose or meal tests. RESEARCH DESIGN AND METHODS: Eligible trials were identified by The Cochrane Library, MEDLINE, Embase, and Web of Science. Data were retrieved and random-effects models for the primary meta-analysis, random-effects meta-regression, and subgroup and regression analyses were applied. RESULTS: Random-effects meta-analysis of GIP responses in 23 trials during 28 different stimulation tests showed that patients with type 2 diabetes (n=363) exhibited no significant differences (P=not significant) in peak plasma GIP, total area under the curve (tAUC), time-corrected tAUC (tAUC×min(-1)), and time-corrected incremental area under the curve (iAUC×min(-1)) in comparison with nondiabetic control subjects (n=325) but had lower GIP responses as evaluated from iAUC (weighted mean difference, -648 pmol/L×min; 95% CI, -1,276 to -21). Fixed-effects models meta-analyses confirmed most of the results of the primary meta-analysis but showed iAUC×min(-1) to be reduced and showed tAUC and tAUC×min(-1) to be higher in diabetic patients. Random-effects meta-regression of the primary meta-analysis showed that age (peak GIP, tAUC, iAUC, and iAUC×min(-1)), BMI (tAUC, iAUC, and iAUC×min(-1)), and HbA1c (iAUC and iAUC×min(-1)) predicted some of the GIP outcomes. Post hoc subgroup analysis showed a negative influence of age and of HbA1c on GIP responses and showed a positive influence of BMI on GIP responses. CONCLUSIONS: Our results suggest that patients with type 2 diabetes are characterized by preserved GIP secretion in response to oral glucose and meal tests. They also suggest that high BMI is associated with increased GIP responses but increasing age and HbA1c are associated with reduced GIP secretion.

Beta and alpha cell function in metabolically healthy but obese subjects: relationship with entero-insular axis.

OBJECTIVE: Obesity is widely acknowledged as a critical risk factor for metabolic complications. Among obese subjects, there is a phenotype of metabolically healthy but obese (MHO) individuals that shows a favorable cardiometabolic risk profile. We aimed to evaluate the potential mechanisms underlying the metabolic profile of this subset, including alpha and beta cell function and entero-insular axis. DESIGN AND METHODS: One hundred twenty-nine obese and 24 nonobese subjects were studied. Obese participants were defined as MHO or at-risk obese, according to the homeostasis model of assessment-insulin resistance (HOMA-IR) index (MHO: lower tertile of HOMA-IR, n = 43; at-risk: upper tertile of HOMA-IR index, n = 41). Insulin, glucagon, and incretin responses after a 120' oral glucose tolerance test (75-g OGTT) were investigated. RESULTS: During OGTT, MHO individuals showed in comparison with at-risk subjects: lower fasting and afterloads plasma levels of glucose, insulin, and C-peptide; higher disposition index; lower fasting (P = 0.004) and at 30' (P = 0.01) plasma glucose-dependent insulinotropic polypeptide (GIP) levels; lower area under the curve (AUC) (0-30) for GIP (P = 0.008); higher glucagon-like peptide-1 (GLP-1) plasma levels at 90' (P = 0.02) and 120' (P = 0.02); lower glucagon plasma levels at baseline (P = 0.04) and at 30' (P = 0.03); and appropriate glucagon suppression after the oral glucose load. CONCLUSIONS: MHO subjects show, as well as normal-weight individuals, a lower diabetogenic profile by virtue of higher disposition index and unaffected entero-insular axis. At-risk obese individuals present increased GIP levels that might play a role in determining increased glucagon secretion and inappropriate glucagon responses after glucose load, thus contributing to impaired glucose homeostasis.

Elevated plasma glucose-dependent insulinotropic polypeptide associates with hyperinsulinemia in metabolic syndrome.

BACKGROUND AND AIMS: Metabolic syndrome (MS) is a high-risk condition for type 2 diabetes, a disease characterized by insulin resistance and insulin secretion abnormalities. Insulin resistance has been widely characterized in MS subjects while insulin secretion has been poorly investigated. The present study was hence undertaken to further investigate the α and ß cell function and entero-insular axis in this pre-diabetic condition. MATERIALS AND METHODS: Using 120' oral glucose tolerance test (OGTT, 75  g) and 60' intravenous glucose tolerance test (IVGTT, 0.3  g/kg), we studied α and ß cell function, insulin resistance, and incretin levels in 96 subjects with normal fasting glucose and normal glucose tolerance to OGTT, with (MS+, n=29) and without MS (MS-, n=67). RESULTS: MS+ individuals showed in comparison with MS-: higher insulinogenic index (IG30) and higher area under the curve (AUC) (0-120) for glucose and insulin during the OGTT, P<0.05; higher AUC (0-10) for glucose (P<0.05) but similar first phase insulin secretion (P=NS) as measured by ΔAIRG and AUC (0-10) for insulin during the IVGTT; increased AUC (0-60) for insulin during the IVGTT (P=0.04); higher GIP levels at 30' (P=0.03), 60' (P=0.01), 90' (P=0.003), and 120' (P=0.004); higher AUC (0-120) for GIP (P=0.007); similar AUC (0-120) for GLP-1 during the OGTT; and delayed glucagon suppression after the OGTT. CONCLUSION: NGT subjects with MS showed increased GIP secretion that could be responsible for the delayed glucagon suppression during the OGTT, thereby suggesting a role for incretins in regulating glucose homeostasis in this condition.