Effects of short-acting exenatide added three times daily to insulin therapy on bone metabolism in type 1 diabetes.

AIM: To evaluate the efficacy of the short-acting glucagon-like peptide-1 receptor agonist, exenatide, added to insulin therapy in type 1 diabetes on bone mineral density and bone turnover markers. MATERIALS AND METHODS: In a randomized, double-blinded, parallel-group trial, 108 individuals with type 1 diabetes aged 18 years or older on basal-bolus therapy with HbA1c 59-88 mmol/mol (7.5%-10.0%) and body mass index of more than 22.0 kg/m2 were randomized (1:1) to preprandial subcutaneous injection of 10 µg exenatide (Byetta) before breakfast, lunch, and dinner over 26 weeks as add-on treatment to insulin therapy. RESULTS: Exenatide elicited a body weight reduction of 4.4 kg compared with placebo, but no between-group differences in bone mineral density, as assessed by whole-body, hip, lumbar, and forearm dual-energy X-ray absorptiometry following 26 weeks of treatment, were observed. Fasting plasma levels of C-terminal telopeptides of type I collagen, a marker of bone resorption, and amino-terminal propeptide of type I procollagen, a marker of bone formation, were unchanged by exenatide compared with placebo after 26 weeks. CONCLUSIONS: Despite an exenatide-induced body weight reduction, no changes in bone metabolism were observed with exenatide added to insulin therapy in type 1 diabetes after 26 weeks.

Once-weekly subcutaneous semaglutide treatment for persons with type 2 diabetes: Real-world data from a diabetes out-patient clinic.

AIMS: The once-weekly administered glucagon-like peptide 1 (GLP-1) receptor agonist (GLP-1RA) semaglutide, has, in clinical trials, demonstrated significant reductions in glycated haemoglobin A1c (HbA1c ) and body weight in persons with type 2 diabetes. We evaluated the real-world clinical effects of semaglutide once weekly in a hospital-based diabetes out-patient clinic. METHODS: This retrospective observational cohort study included persons with type 2 diabetes (n = 119) on a broad range of antidiabetic medicine: GLP-1RA naïve persons (n = 37) and GLP-1RA-experienced persons (n = 82). Person characteristics at inclusion: age [median (quartiles)]: 65 (57, 72) years; body weight 99 (86, 118) kg; body mass index (BMI) 33 (29, 38) kg/m²; HbA1c 61 (54, 69) mmol/mol/(7.7 (7.1, 8.5) %). Data were collected at baseline and after 3, 6 and 12 months of semaglutide treatment. Data were analysed using a general linear mixed model for repeated measurements. RESULTS: After 12 months, the reductions in HbA1c were (mean [95% confidence interval]: GLP-1RA naïve: -12.8 [-17.0, -8.5] mmol/mol/ -1.2 [-1.6, -0.8]% (p < 0.01) and GLP-1RA experienced: -6.4 [-9.0, -3.8] mmol/mol/ -0.6 [-0.8, -0.4]% (p < 0.01), respectively. Body weight reductions in GLP-1RA naïve: -5 [-6.9, -3.1] kg (p < 0.01) and GLP-1RA experienced: -3.2 [-4.4, -2.0] kg (p < 0.01), respectively. Seventy-five percent received 1 mg QW semaglutide. CONCLUSION: We observed effects of semaglutide once weekly on HbA1c and body weight comparable with the effects observed in clinical studies with fewer persons in our cohort receiving maximum dose of semaglutide.

The GLP-1 receptor agonist lixisenatide reduces postprandial glucose in patients with diabetes secondary to total pancreatectomy: a randomised, placebo-controlled, double-blinded crossover trial.

AIMS/HYPOTHESIS: Treatment of diabetes secondary to total pancreatectomy remains a challenge and insulin constitutes the only glucose-lowering treatment for these patients. We hypothesised that the glucagon-like peptide 1 (GLP-1) receptor agonist lixisenatide would improve postprandial glucose tolerance in totally pancreatectomised patients. METHODS: In a double-blinded, randomised, crossover study, 12 totally pancreatectomised individuals (age: 65.0 ± 9.5 mean±SD years; BMI: 22.9 ± 3.9 kg/m2) and 12 healthy control individuals (age 66.1 ± 7.6 years; BMI: 24.0 ± 2.9 kg/m2) underwent two 3 h liquid mixed-meal tests (with paracetamol for assessment of gastric emptying) after single-dose injection of 20 µg of lixisenatide or placebo. Basal insulin was given the night before each experimental day; no insulin was given during study days. RESULTS: Compared with placebo, lixisenatide reduced postprandial plasma glucose excursions in the pancreatectomy group (baseline-subtracted AUC [bsAUC] [mean±SEM]: 548 ± 125 vs 1447 ± 95 mmol/l × min, p < 0.001) and in the control group (-126 ± 12 vs 222 ± 51 mmol/l × min, p < 0.001). In the pancreatectomy group a mean peak glucose concentration of 23.3 ± 1.0 mmol/l was reached at time point 134 ± 11 min with placebo, compared with a mean peak glucose concentration of 18 ± 1.4 mmol/l (p = 0.008) at time point 148 ± 13 min (p = 0.375) with lixisenatide. In the control group a mean peak concentration of 8.2 ± 0.4 mmol/l was reached at time point 70 ± 13 min with placebo, compared with a mean peak concentration of 5.5 ± 0.1 mmol/l (p < 0.001) at time point 8 ± 25 min (p = 0.054) with lixisenatide. Lixisenatide also reduced gastric emptying and postprandial glucagon responses in the pancreatectomy group (66 ± 84 vs 1190 ± 311 pmol/l × min, p = 0.008) and in the control group (141 ± 100 vs 190 ± 100 pmol/l × min, p = 0.034). In the pancreatectomy group, C-peptide was undetectable in plasma. In the control group, postprandial plasma C-peptide responses were reduced with lixisenatide (18 ± 17 vs 189 ± 31 nmol/l × min, p < 0.001). CONCLUSIONS/INTERPRETATION: The GLP-1 receptor agonist lixisenatide reduces postprandial plasma glucose excursions in totally pancreatectomised patients. The mode of action seems to involve deceleration of gastric emptying and reduced postprandial responses of gut-derived glucagon. TRIAL REGISTRATION: ClinicalTrials.gov NCT02640118. FUNDING: This study was funded by an unrestricted investigator-initiated study grant from Sanofi. Support was also received from from the Novo Nordisk Foundation Center for Basic Metabolic Research, the A.P. Møller Foundation for the Advancement of Medical Science and the Faculty of Health and Medical Sciences, University of Copenhagen.

Effect of short-acting exenatide administered three times daily on markers of cardiovascular disease in type 1 diabetes: A randomized double-blind placebo-controlled trial.

AIMS: To investigate the effect of adding the short-acting glucagon-like peptide 1 receptor agonist (GLP-1RA) exenatide to insulin treatment on markers of cardiovascular risk in type 1 diabetes. MATERIALS AND METHODS: In a randomized, double-blind, parallel-group trial, 108 individuals with type 1 diabetes aged ≥18 years on multiple daily injection therapy with a body mass index >22.0 kg/m2 and glycated haemoglobin concentration of 59 to 88 mmol/mol (7.5%-10.0%) were randomized (1:1) to preprandial subcutaneous injection of 10 µg exenatide (Byetta®) or placebo three times daily over 26 weeks as add-on treatment to existing insulin therapy. Reported markers of cardiovascular risk were secondary endpoints and were analyzed in a baseline-adjusted linear mixed model in the intention-to-treat population. The primary results of this study, the MAG1C (Meal-time Administration of exenatide for Glycaemic control in type 1 diabetes Cases) trial, were previously reported. RESULTS: Exenatide changed total fat mass by -2.6 kg (95% confidence interval [CI] -3.6; -1.6; P < 0.0001) and lean body mass by -1.1 kg (95% CI -1.9; -0.4; P = 0.01) compared with placebo, as assessed by dual-energy X-ray absorptiometry. Fat mass reductions were similar for central and peripheral fat mass. Exenatide did not change levels of interleukin-2 or -6; tumour necrosis factor-α; C-reactive protein; N-terminal prohormone of brain natriuretic peptide; or 8-oxo-7,8-dihydroguanosine (RNA oxidation marker) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (DNA oxidation marker). CONCLUSIONS: Exenatide added to insulin therapy in type 1 diabetes for 26 weeks resulted in body weight loss primarily from fat mass reduction, but had no effect on biomarkers of cardiovascular disease risk.

Effects of combined GIP and GLP-1 infusion on energy intake, appetite and energy expenditure in overweight/obese individuals: a randomised, crossover study.

AIMS/HYPOTHESIS: Glucagon-like peptide 1 (GLP-1) reduces appetite and energy intake in humans, whereas the other incretin hormone, glucose-dependent insulinotropic polypeptide (GIP), seems to have no effect on eating behaviour. Interestingly, studies in rodents have shown that concomitant activation of GIP and GLP-1 receptors may potentiate the satiety-promoting effect of GLP-1, and a novel dual GLP-1/GIP receptor agonist was recently shown to trigger greater weight losses compared with a GLP-1 receptor agonist in individuals with type 2 diabetes. The aim of this study was to delineate the effects of combined GIP and GLP-1 receptor activation on energy intake, appetite and resting energy expenditure in humans. METHODS: We examined 17 overweight/obese men in a crossover design with 5 study days. On day 1, a 50 g OGTT was performed; on the following 4 study days, the men received an isoglycaemic i.v. glucose infusion (IIGI) plus saline (154 mmol/l NaCl; placebo), GIP (4 pmol kg-1 min-1), GLP-1 (1 pmol kg-1 min-1) or GIP+GLP-1 (4 and 1 pmol kg-1 min-1, respectively). All IIGIs were performed in a randomised order blinded for the participant and the investigators. The primary endpoint was energy intake as measured by an ad libitum meal after 240 min. Secondary endpoints included appetite ratings and resting energy expenditure, as well as insulin, C-peptide and glucagon responses. RESULTS: Energy intake was significantly reduced during IIGI+GLP-1 compared with IIGI+saline infusion (2715 ± 409 vs 4483 ± 568 kJ [mean ± SEM, n = 17], p = 0.014), whereas there were no significant differences in energy intake during IIGI+GIP (4062 ± 520 kJ) or IIGI+GIP+GLP-1 (3875 ± 451 kJ) infusion compared with IIGI+saline (p = 0.590 and p = 0.364, respectively). Energy intake was higher during IIGI+GIP+GLP-1 compared with IIGI+GLP-1 infusion (p = 0.039). CONCLUSIONS/INTERPRETATION: While GLP-1 infusion lowered energy intake in overweight/obese men, simultaneous GIP infusion did not potentiate this GLP-1-mediated effect. TRIAL REGISTRATION: ClinicalTrials.gov NCT02598791 FUNDING: This study was supported by grants from the Innovation Fund Denmark and the Vissing Foundation.

Hepatic transcriptome signatures in patients with varying degrees of nonalcoholic fatty liver disease compared with healthy normal-weight individuals.

Nonalcoholic fatty liver disease (NAFLD) represents a spectrum of conditions ranging from simple steatosis (NAFL), over nonalcoholic steatohepatitis (NASH) with or without fibrosis, to cirrhosis with end-stage disease. The hepatic molecular events underlying the development of NAFLD and transition to NASH are poorly understood. The present study aimed to determine hepatic transcriptome dynamics in patients with NAFL or NASH compared with healthy normal-weight and obese individuals. RNA sequencing and quantitative histomorphometry of liver fat, inflammation and fibrosis were performed on liver biopsies obtained from healthy normal-weight ( n = 14) and obese ( n = 12) individuals, NAFL ( n = 15) and NASH ( n = 16) patients. Normal-weight and obese subjects showed normal liver histology and comparable gene expression profiles. Liver transcriptome signatures were largely overlapping in NAFL and NASH patients, however, clearly separated from healthy normal-weight and obese controls. Most marked pathway perturbations identified in both NAFL and NASH were associated with markers of lipid metabolism, immunomodulation, extracellular matrix remodeling, and cell cycle control. Interestingly, NASH patients with positive Sonic hedgehog hepatocyte staining showed distinct transcriptome and histomorphometric changes compared with NAFL. In conclusion, application of immunohistochemical markers of hepatocyte injury may serve as a more objective tool for distinguishing NASH from NAFL, facilitating improved resolution of hepatic molecular changes associated with progression of NAFLD. NEW & NOTEWORTHY Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease in Western countries. NAFLD is associated with the metabolic syndrome and can progress to the more serious form, nonalcoholic steatohepatitis (NASH), and ultimately lead to irreversible liver damage. Using gold standard molecular and histological techniques, this study demonstrates that the currently used diagnostic tools are problematic for differentiating mild NAFLD from NASH and emphasizes the marked need for developing improved histological markers of NAFLD progression.

The Effects of Dual GLP-1/GIP Receptor Agonism on Glucagon Secretion-A Review.

The gut-derived incretin hormones glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are secreted after meal ingestion and work in concert to promote postprandial insulin secretion. Furthermore, GLP-1 inhibits glucagon secretion when plasma glucose concentrations are above normal fasting concentrations while GIP acts glucagonotropically at low glucose levels. A dual incretin receptor agonist designed to co-activate GLP-1 and GIP receptors was recently shown to elicit robust improvements of glycemic control (mean haemoglobin A1c reduction of 1.94%) and massive body weight loss (mean weight loss of 11.3 kg) after 26 weeks of treatment with the highest dose (15 mg once weekly) in a clinical trial including overweight/obese patients with type 2 diabetes. Here, we describe the mechanisms by which the two incretins modulate alpha cell secretion of glucagon, review the effects of co-administration of GLP-1 and GIP on glucagon secretion, and discuss the potential role of glucagon in the therapeutic effects observed with novel unimolecular dual GLP-1/GIP receptor agonists. For clinicians and researchers, this manuscript offers an understanding of incretin physiology and pharmacology, and provides mechanistic insight into future antidiabetic and obesity treatments.

Is glucagon-like peptide-1 fully protected by the dipeptidyl peptidase 4 inhibitor sitagliptin when administered to patients with type 2 diabetes?

AIM: To evaluate the relationship between plasma dipeptidyl-peptidase 4 (DPP-4) activity and its protection of glucagon-like peptide-1 (GLP-1) using the DPP-4 inhibitor sitagliptin. METHODS: On four separate days, patients with type 2 diabetes (T2D) (n = 8; age: 59.9 ±10.8 [mean ±SD] years; body mass index [BMI]: 28.8 ±4.6 kg/m2 ; glycated haemoglobin A1c [HbA1c]: 43.1 ±0.5 mmol/mol [6.6% ±1.7%]) received a 380-minute continuous intravenous infusion of GLP-1 (1.0 pmol × kg bodyweight-1 × minutes-1 ) and a double-blind, single-dose oral administration of sitagliptin in doses of 0 (placebo), 25, 100 and 200 mg. RESULTS: Plasma DPP-4 activity decreased compared to baseline (placebo) with increasing doses of sitagliptin (P < .01), reaching a maximal inhibition with the 100 mg dose. Levels of intact GLP-1 increased with increasing doses of sitagliptin from placebo to 100 mg (area under curve [AUC] 7.2 [95%, CI; 12.1, 16.4] [placebo], 10.7 [16.1, 21.4] [25 mg], 11.7 [17.8, 23.6] [100 mg] nmol/L × 360 minutes [P < .01]), but no further increase in intact GLP-1 levels was observed with 200 mg of sitagliptin (11.5 [17.6, 23.4] nmol/L × 360 minutes) (P = .80). CONCLUSION: Our findings suggest that the sitagliptin dose of 100 mg is sufficient to inhibit both plasma and membrane-bound DPP-4 activity, presumably also leading to complete protection of endogenous GLP-1 in patients with T2D.

Glucagon responses to increasing oral loads of glucose and corresponding isoglycaemic intravenous glucose infusions in patients with type 2 diabetes and healthy individuals.

AIMS/HYPOTHESIS: Type 2 diabetes is associated with hypersecretion of glucagon during an OGTT, whereas i.v. glucose suppresses glucagon levels. This suggests that type 2 diabetic hyperglucagonaemia may result from glucose stimulation of the gastrointestinal tract. We evaluated glucagon responses to increasing amounts of glucose given orally and corresponding isoglycaemic i.v. glucose infusions (IIGIs) in patients with type 2 diabetes and in healthy controls. METHODS: Plasma glucagon responses were measured during three 4 h OGTTs with increasing loads of glucose (25 g, 75 g and 125 g) and three corresponding IIGIs in eight patients with type 2 diabetes (age [mean ± SEM] 57 ± 4 years; BMI 29.5 ± 1.0 kg/m(2); HbA1c 7.0 ± 0.3% [53 ± 2 mmol/mol]) and eight healthy individuals (age 57 ± 4 years; BMI 28.9 ± 0.7 kg/m(2); HbA1c 5.4 ± 0.1% [36 ± 1 mmol/mol]). RESULTS: In healthy controls no difference in glucagon suppression during the first 45 min of the 25 g OGTT and the corresponding IIGI (-153 ± 35 vs -133 ± 24 min × pmol/l; p = NS) was observed, whereas patients with type 2 diabetes only exhibited significant glucagon suppression following IIGI (29 ± 27 vs -144 ± 20 min × pmol/l; p = 0.005). At higher oral glucose loads this difference increased and also became evident in healthy controls. CONCLUSIONS/INTERPRETATION: In patients with type 2 diabetes increasing amounts of oral glucose elicit hypersecretion of glucagon, whereas corresponding IIGIs result in significant glucagon suppression; a phenomenon that is also observed in healthy individuals when larger glucose loads are ingested orally. This suggests that the hyperglucagonaemic response to oral glucose in type 2 diabetes may represent a pathological version of a gut-derived physiological phenomenon. TRIAL REGISTRATION: ClinicalTrials.gov NCT00529048.

Glucagon and type 2 diabetes: the return of the alpha cell.

In normal physiology, glucagon from pancreatic alpha cells plays an important role in maintaining glucose homeostasis via its regulatory effect on hepatic glucose production. Patients with type 2 diabetes suffer from fasting and postprandial hyperglucagonemia, which stimulate hepatic glucose production and, thus, contribute to the hyperglycemia characterizing these patients. Although this has been known for years, research focusing on alpha cell (patho)physiology has historically been dwarfed by research on beta cells and insulin. Today the mechanisms behind type 2 diabetic hyperglucagonemia are still poorly understood. Preclinical and clinical studies have shown that the gastrointestinal hormone glucose-dependent insulinotropic polypeptide (GIP) might play an important role in this pathophysiological phenomenon. Furthermore, it has become apparent that suppression of glucagon secretion or antagonization of the glucagon receptor constitutes potentially effective treatment strategies for patients with type 2 diabetes. In this review, we focus on the regulation of glucagon secretion by the incretin hormones glucagon-like peptide-1 (GLP-1) and GIP. Furthermore, potential advantages and limitations of suppressing glucagon secretion or antagonizing the glucagon receptor, respectively, in the treatment of patients with type 2 diabetes will be discussed.

Targeting the GLP-2 receptor in the management of obesity.

Recent advancements in understanding glucagon-like peptide 2 (GLP-2) biology and pharmacology have sparked interest in targeting the GLP-2 receptor (GLP-2R) in the treatment of obesity. GLP-2 is a proglucagon-derived 33-amino acid peptide co-secreted from enteroendocrine L cells along with glucagon-like peptide 1 (GLP-1) and has a range of actions via the GLP-2R, which is particularly expressed in the gastrointestinal tract, the liver, adipose tissue, and the central nervous system (CNS). In humans, GLP-2 evidently induces intestinotrophic effects (i.e., induction of intestinal mucosal proliferation and improved gut barrier function) and promotes mesenteric blood flow. However, GLP-2 does not seem to have appetite or food intake-reducing effects in humans, but its gut barrier-promoting effect may be of interest in the context of obesity. Obesity is associated with reduced gut barrier function, increasing the translocation of proinflammatory gut content to the circulation. This phenomenon constitutes a strong driver of obesity-associated systemic low-grade inflammation, which in turn plays a major role in the development of most obesity-associated complications. Thus, the intestinotrophic and gut barrier-improving effect of GLP-2, which in obese rodent models shows strong anti-inflammatory potential, may, in combination with food intake-reducing strategies, e.g., GLP-1 receptor (GLP-1) agonism, be able to rectify core pathophysiological mechanism of obesity. Here, we provide an overview of GLP-2 physiology in the context of obesity pathophysiology and review the pharmacological potential of GLP-2R activation in the management of obesity and related comorbidities.

Empagliflozin Normalizes Fasting Hyperglycemia and Improves Postprandial Glucose Tolerance in Totally Pancreatectomized Patients: A Randomized, Double-Blind, Placebo-Controlled Crossover Study.

OBJECTIVE: Insulin remains the only glucose-lowering treatment modality recommended for totally pancreatectomized patients. We investigated the effects of the sodium-glucose cotransporter 2 inhibitor empagliflozin on fasting and postprandial glucose concentrations in pancreatectomized patients and matched healthy control participants. RESEARCH DESIGN AND METHODS: In a randomized, double-blind, placebo-controlled crossover study, 10 pancreatectomized patients and 10 matched control participants underwent two 3-h liquid mixed meal tests preceded by two doses of 25 mg empagliflozin (administered the night before and in the morning of the meal test) or placebo, respectively. Basal insulin was administered as usual, but bolus insulin was omitted before the meal test during experimental days. RESULTS: Compared with placebo, empagliflozin lowered fasting plasma glucose (5.0 ± 0.4 vs. 7.9 ± 0.9 mmol/L [mean ± SEM], P = 0.007) and postprandial plasma glucose excursions as assessed by baseline-subtracted area under the curve (1,080 [733; 1,231] vs. 1,169 [1,036; 1,417] pmol/L × min [median (25th and 75th percentiles)], P = 0.014) in the pancreatectomized patients. In the control participants, empagliflozin lowered fasting plasma glucose compared with placebo (5.1 ± 0.1 vs. 5.5 ± 0.1 mmol/L, P = 0.008) without affecting postprandial glucose excursions significantly. The pancreatomy group exhibited greater postprandial glucagon excursions compared with the control group on both experimental days (P ≤ 0.015); no within-group differences between days were observed. CONCLUSIONS: Empagliflozin administered the day before and immediately before a standardized liquid mixed meal test normalized fasting hyperglycemia and improved postprandial glucose tolerance in pancreatectomized patients.

Increased hepatic glucagon sensitivity in totally pancreatectomised patients.

OBJECTIVE: The metabolic phenotype of totally pancreatectomised patients includes hyperaminoacidaemia and predisposition to hypoglycaemia and hepatic lipid accumulation. We aimed to investigate whether the loss of pancreatic glucagon may be responsible for these changes. METHODS: Nine middle-aged, normal-weight totally pancreatectomised patients, nine patients with type 1 diabetes (C-peptide negative), and nine matched controls underwent two separate experimental days, each involving a 150-min intravenous infusion of glucagon (4 ng/kg/min) or placebo (saline) under fasting conditions while any basal insulin treatment was continued. RESULTS: Glucagon infusion increased plasma glucagon to similar high physiological levels in all groups. The infusion increased hepatic glucose production and decreased plasma concentration of most amino acids in all groups, with more pronounced effects in the totally pancreatectomised patients compared with the other groups. Glucagon infusion diminished fatty acid re-esterification and tended to decrease plasma concentrations of fatty acids in the totally pancreatectomised patients but not in the type 1 diabetes patients. CONCLUSION: Totally pancreatectomised patients were characterised by increased sensitivity to exogenous glucagon at the level of hepatic glucose, amino acid, and lipid metabolism, suggesting that the metabolic disturbances characterising these patients may be rooted in perturbed hepatic processes normally controlled by pancreatic glucagon.

Gluco-metabolic response to exogenous oxytocin in totally pancreatectomized patients and healthy individuals.

Oxytocin has been proposed to possess glucose-stabilizing effects through the release of insulin and glucagon from the pancreas. Also, exogenous oxytocin has been shown to stimulate extrapancreatic glucagon secretion in depancreatized dogs. Here, we investigated the effect of exogenous oxytocin on circulating levels of pancreatic and gut-derived glucose-stabilizing hormones (insulin [measured as C-peptide], glucagon, glucagon-like peptide 1 [GLP-1], and glucose-dependent insulinotropic polypeptide). We studied nine pancreatectomized (PX) patients and nine healthy controls (CTRLs) (matched on age and body mass index) before, during, and after an intravenous infusion of 10 IU of oxytocin administered over 12 min. Oxytocin did not increase plasma glucagon levels, nor induce any changes in plasma glucose, C-peptide, or GIP in any of the groups. Oxytocin decreased plasma glucagon levels by 19 ± 10 % in CTRLs (from 2.0 ± 0.5 [mean ± SEM] to 1.3 ± 0.2 pmol/l, P = 0.0025) and increased GLP-1 by 42 ± 22 % in PX patients (from 9.0 ± 1.0-12.7 ± 1.0 pmol/l, P = 0.0003). Fasting plasma glucose levels were higher in PX patients compared with CTRLs (13.1 ± 1.1 vs. 5.1 ± 0.1 mmol/l, P < 0.0001). In conclusion, the present findings do not support pancreas-mediated glucose-stabilizing effects of acute oxytocin administration in humans and warrant further investigation of oxytocin's gluco-metabolic effects.

Hyperglucagonaemia and amino acid alterations in individuals with type 2 diabetes and non-alcoholic fatty liver disease.

Aims: Hyperglucagonaemia contributes to the pathophysiology in type 2 diabetes (T2D), but the mechanisms behind the inappropriate glucagon secretion are not fully understood. Glucagon and amino acids are regulated in a feedback loop referred to as the liver-α cell axis. Individuals with non-alcoholic fatty liver disease (NAFLD) appear to be glucagon resistant, disrupting the liver-α cell axis resulting in hyperglucagonaemia and hyperaminoacidaemia. We investigated the associations between circulating glucagon, amino acids, and liver fat content in a cohort of individuals with T2D. Methods: We included 110 individuals with T2D in this cross-sectional study. Liver fat content was quantified using 1H magnetic resonance spectroscopy (MRS). Associations between liver fat content and plasma glucagon and amino acids, respectively, were estimated in multivariate linear regression analyses. Results: Individuals with NAFLD (n = 52) had higher plasma glucagon concentrations than individuals without NAFLD (n = 58). The positive association between plasma glucagon concentrations and liver fat content was confirmed in the multivariable regression analyses. Plasma concentrations of isoleucine and glutamate were increased, and glycine and serine concentrations were decreased in individuals with NAFLD. Concentrations of other amino acids were similar between individuals with and without NAFLD, and no clear association was seen between liver fat content and amino acids in the regression analyses. Conclusion: MRS-diagnosed NAFLD in T2D is associated with hyperglucagonaemia and elevated plasma concentrations of isoleucine and glutamate and low plasma concentrations of glycine and serine. Whether NAFLD and glucagon resistance per se induce these changes remains to be elucidated.

The effect of exogenous glucagon on circulating amino acids in individuals with and without type 2 diabetes and obesity.

Objective: In obesity and type 2 diabetes, hyperglucagonaemia may be caused by elevated levels of glucagonotropic amino acids due to hepatic glucagon resistance at the level of amino acid turnover. Here, we investigated the effect of exogenous glucagon on circulating amino acids in obese and non-obese individuals with and without type 2 diabetes. Design: This was a post hoc analysis in a glucagon infusion study performed in individuals with type 2 diabetes (n = 16) and in age, sex, and body mass index-matched control individuals without diabetes (n = 16). Each group comprised two subgroups of eight individuals with and without obesity, respectively. Methods: All participants received a 1-h glucagon infusion (4 ng/kg/min) in the overnight fasted state. Plasma amino acid concentrations were measured with frequent intervals. Results: Compared to the control subgroup without obesity, baseline total amino acid levels were elevated in the control subgroup with obesity and in the type 2 diabetes subgroup without obesity. In all subgroups, amino acid levels decreased by up to 20% in response to glucagon infusion, which resulted in high physiological steady-state glucagon levels (mean concentration: 74 pmol/L, 95% CI [68;79] pmol/L). Following correction for multiple testing, no intergroup differences in changes in amino acid levels reached significance. Conclusion: Obesity and type 2 diabetes status was associated with elevated fasting levels of total amino acids. The glucagon infusion decreased circulating amino acid levels similarly in all subgroups, without significant differences in the response to exogenous glucagon between individuals with and without obesity and type 2 diabetes. Significance statement: The hormone glucagon stimulates glucose production from the liver, which may promote hyperglycaemia if glucagon levels are abnormally elevated, as is often seen in type 2 diabetes and obesity. Glucagon levels are closely linked to, and influenced by, the levels of circulating amino acids. To further investigate this link, we measured amino acid levels in individuals with and without obesity and type 2 diabetes before and during an infusion of glucagon. We found that circulating amino acid levels were higher in type 2 diabetes and obesity, and that glucagon infusion decreased amino acid levels in both individuals with and without type 2 diabetes and obesity. The study adds novel information to the link between circulating levels of glucagon and amino acids.

Glucagon Clearance Is Decreased in Chronic Kidney Disease but Preserved in Liver Cirrhosis.

It is not completely clear which organs are responsible for glucagon elimination in humans, and disturbances in the elimination of glucagon could contribute to the hyperglucagonemia observed in chronic liver disease and chronic kidney disease (CKD). Here, we evaluated kinetics and metabolic effects of exogenous glucagon in individuals with stage 4 CKD (n = 16), individuals with Child-Pugh A-C cirrhosis (n = 16), and matched control individuals (n = 16), before, during, and after a 60-min glucagon infusion (4 ng/kg/min). Individuals with CKD exhibited a significantly lower mean metabolic clearance rate of glucagon (14.0 [95% CI 12.2;15.7] mL/kg/min) compared with both individuals with cirrhosis (19.7 [18.1;21.3] mL/kg/min, P < 0.001) and control individuals (20.4 [18.1;22.7] mL/kg/min, P < 0.001). Glucagon half-life was significantly prolonged in the CKD group (7.5 [6.9;8.2] min) compared with individuals with cirrhosis (5.7 [5.2;6.3] min, P = 0.002) and control individuals (5.7 [5.2;6.3] min, P < 0.001). No difference in the effects of exogenous glucagon on plasma glucose, amino acids, or triglycerides was observed between groups. In conclusion, CKD, but not liver cirrhosis, leads to a significant reduction in glucagon clearance, supporting the kidneys as a primary site for human glucagon elimination.

The glucagon receptor antagonist LY2409021 does not affect gastrointestinal-mediated glucose disposal or the incretin effect in individuals with and without type 2 diabetes.

Objective: Gastrointestinal-mediated glucose disposal (GIGD) during oral glucose tolerance test (OGTT) reflects the percentage of glucose disposal caused by mechanisms elicited by the oral route of glucose administration. GIGD is reduced in patients with type 2 diabetes (T2D) due to a reduced incretin effect and possibly also due to inappropriate suppression of glucagon after oral glucose. We investigated the effect of glucagon receptor antagonism on GIGD, the incretin effect and glucose excursions in patients with T2D and controls without diabetes. Design: A double-blind, randomised, placebo-controlled crossover study was conducted. Methods: Ten patients with T2D and 10 gender-, age- and BMI-matched controls underwent two 50 g OGTTs and 2 isoglycaemic i.v. glucose infusions, succeeding (~10 h) single-dose administration of 100 mg of the glucagon receptor antagonist LY2409021 or placebo, respectively. Results: Compared to placebo, LY2409021 reduced fasting plasma glucose in patients with T2D and controls. Plasma glucose excursions after oral glucose assessed by baseline-subtracted area under the curve were increased by LY2409021 compared to placebo in both groups, but no effect of LY2409021 on GIGD or the incretin effect was observed. LY2409021 increased fasting glucagon concentrations three-fold compared to placebo concentrations. Conclusions: Glucagon receptor antagonism with LY2409021 had no effect on the impaired GIGD or the impaired incretin effect in patients with T2D and did also not affect these parameters in the controls. Surprisingly, we observed reduced oral glucose tolerance with LY2409021 which may be specific for this glucagon receptor antagonist.

THERAPY OF ENDOCRINE DISEASE: Amylin and calcitonin - physiology and pharmacology.

Type 2 diabetes is a common manifestation of metabolic dysfunction due to obesity and constitutes a major burden for modern health care systems, in concert with the alarming rise in obesity worldwide. In recent years, several successful pharmacotherapies improving glucose metabolism have emerged and some of these also promote weight loss, thus, ameliorating insulin resistance. However, the progressive nature of type 2 diabetes is not halted by these new anti-diabetic pharmacotherapies. Therefore, novel therapies promoting weight loss further and delaying diabetes progression are needed. Amylin, a beta cell hormone, has satiating properties and also delays gastric emptying and inhibits postprandial glucagon secretion with the net result of reducing postprandial glucose excursions. Amylin acts through the six amylin receptors, which share the core component with the calcitonin receptor. Calcitonin, derived from thyroid C cells, is best known for its role in humane calcium metabolism, where it inhibits osteoclasts and reduces circulating calcium. However, calcitonin, particularly of salmon origin, has also been shown to affect insulin sensitivity, reduce the gastric emptying rate and promote satiation. Preclinical trials with agents targeting the calcitonin receptor and the amylin receptors, show improvements in several parameters of glucose metabolism including insulin sensitivity and some of these agents are currently undergoing clinical trials. Here, we review the physiological and pharmacological effects of amylin and calcitonin and discuss the future potential of amylin and calcitonin-based treatments for patients with type 2 diabetes and obesity.

The glucagon receptor antagonist LY2409021 has no effect on postprandial glucose in type 2 diabetes.

OBJECTIVE: Type 2 diabetes (T2D) pathophysiology includes fasting and postprandial hyperglucagonemia, which has been linked to hyperglycemia via increased endogenous glucose production (EGP). We used a glucagon receptor antagonist (LY2409021) and stable isotope tracer infusions to investigate the consequences of hyperglucagonemia in T2D. DESIGN: A double-blinded, randomized, placebo-controlled crossover study was conducted. METHODS: Ten patients with T2D and ten matched non-diabetic controls underwent two liquid mixed meal tests preceded by single-dose administration of LY2409021 (100 mg) or placebo. Double-tracer technique was used to quantify EGP. Antagonist selectivity toward related incretin receptors was determined in vitro. RESULTS: Compared to placebo, LY2409021 lowered the fasting plasma glucose (FPG) from 9.1 to 7.1 mmol/L in patients and from 5.6 to 5.0 mmol/L in controls (both P < 0.001) by mechanisms involving reduction of EGP. Postprandial plasma glucose excursions (baseline-subtracted area under the curve) were unaffected by LY2409021 in patients and increased in controls compared to placebo. Glucagon concentrations more than doubled during glucagon receptor antagonism. The antagonist interfered with both glucagon-like peptide 1 and glucose-dependent insulinotropic polypeptide receptors, complicating the interpretation of the postprandial data. CONCLUSIONS: LY2409021 lowered FPG concentrations but did not improve postprandial glucose tolerance after a meal in patients with T2D and controls. The metabolic consequences of postprandial hyperglucagonemia are difficult to evaluate using LY2409021 because of its antagonizing effects on the incretin receptors.