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Glucagon-like peptide-1 (GLP-1) receptor agonists are established pharmaceutical therapies for the treatment of type 2 diabetes and obesity. They mimic the action of GLP-1 to reduce glucose levels through stimulation of insulin secretion and inhibition of glucagon secretion. They also reduce body weight by inducing satiety through central actions. The GLP-1 receptor agonists used clinically are based on exendin-4 and native GLP-1 and are available as formulations for daily or weekly s.c. or oral administration. GLP-1 receptor agonism is also achieved by inhibitors of dipeptidyl peptidase-4 (DPP-4), which prevent the inactivation of GLP-1 and glucose-dependent insulinotropic polypeptide (GIP), thereby prolonging their raised levels after meal ingestion. Other developments in GLP-1 receptor agonism include the formation of small orally available agonists and compounds with the potential to pharmaceutically stimulate GLP-1 secretion from the gut. In addition, GLP-1/glucagon and GLP-1/GIP dual receptor agonists and GLP-1/GIP/glucagon triple receptor agonists have shown the potential to reduce blood glucose levels and body weight through their effects on islets and peripheral tissues, improving beta cell function and stimulating energy expenditure. This review summarises developments in gut hormone-based therapies and presents the future outlook for their use in type 2 diabetes and obesity. Graphical Abstract

Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are important incretin hormones. They are released from the gut after meal ingestion and potentiate glucose-stimulated insulin secretion. Their release after meal ingestion and oral glucose are well established and have been characterized previously. During recent years, knowledge of other regulatory aspects that potentially may affect GIP and GLP-1 secretion after meal ingestion have also begun to emerge. Here, the results of human studies on these novel aspects of meal- and nutrient-stimulated incretin hormone secretion are reviewed.The human literature was revisited by identifying articles in PubMed using key words GIP, GLP-1, secretion, meal, and nutrients.The results show that all macronutrients individually stimulate GIP and GLP-1 secretion. However, there was no synergistic action when given in combination. A pre-load 30 min before a meal augments the GIP and GLP-1 response. GIP and GLP-1 secretion have a diurnal variation with a higher response to an identical meal in the morning than in the afternoon. There is no difference in GIP and GLP-1 secretion whether a meal is ingested slowly or rapidly. GIP and GLP-1 secretion after dinner are the same whether or not breakfast and lunch have been ingested. The temperature of the food may be of importance for the incretin hormone response.These novel findings have increased our knowledge on the regulation of the complexity of the incretin system and are also important knowledge when designing future studies.

BCAAs are key ingredients of WPs with biomodulatory effects. We recently reported that a highly-concentrated low-dose (10g, 40 Cal) WP pre-meal drink (125 mL) , generated with novel micelle-technology (WP microgel [WPM]) , ingested 15 min ahead of a pizza-meal (622 Cal) , vs placebo (PBO) , reduced the 2h incremental area under the glucose curve (iAUC) by 22%, increased 2h GLP-1 iAUC by 61% and, delayed 1h gastric emptying by 17%, in 26 people with T2D. Here, we analyzed 2h free plasma BCAA trajectories in 25 persons (mean age 62 yrs, HbA1c 7,5%, BMI 29 kg/m2) that completed this single dose study. The pre-meal WPM drink significantly altered the BCAA trajectory vs. PBO (Figure) . For leucine, ΔiAUCWPM vs PBO increased by 267%, with a shorter time to maximum (median ΔTmax [min, max]: -60 [-120,0] min, p Disclosure I.Neeland: Advisory Panel; Boehringer Ingelheim International GmbH, Merck & Co., Inc., Consultant; Nestlé Health Science. B.Ahrén: Speaker's Bureau; Nestlé, Novo Nordisk, Stock/Shareholder; AstraZeneca, Novo Nordisk A/S. J.V.Corthésy: Employee; Nestlé. Y.Grzywinski: None. Z.Magos: Consultant; Nestlé Health Science. M.Von eynatten: Employee; Nestlé Health Science. O.Johansen: Employee; Boehringer Ingelheim International GmbH, Nestlé Health Science. Funding Nestlé Health Science

Background: glucagon secretion and inhibition should be mainly determined by glucose and insulin levels, but the relative relevance of each factor is not clarified, especially following ingestion of different macronutrients. We aimed to investigate the associations between plasma glucagon, glucose, and insulin after ingestion of single macronutrients or mixed-meal. Methods: thirty-six participants underwent four metabolic tests, based on administration of glucose, protein, fat, or mixed-meal. Glucagon, glucose, insulin, and C-peptide were measured at fasting and for 300 min following food ingestion. We analyzed relationships between time samples of glucagon, glucose, and insulin in each individual, as well as between suprabasal area-under-the-curve of the same variables (ΔAUCGLUCA, ΔAUCGLU, ΔAUCINS) over the whole participants’ cohort. Results: in individuals, time samples of glucagon and glucose were related in only 26 cases (18 direct, 8 inverse relationships), whereas relationship with insulin was more frequent (60 and 5, p < 0.0001). The frequency of significant relationships was different among tests, especially for direct relationships (p ≤ 0.006). In the whole cohort, ΔAUCGLUCA was weakly related to ΔAUCGLU (p ≤ 0.02), but not to ΔAUCINS, though basal insulin secretion emerged as possible covariate. Conclusions: glucose and insulin are not general and exclusive determinants of glucagon secretion/inhibition after mixed-meal or macronutrients ingestion.

The aim of this study was to investigate whether incretins, at physiological levels, affect hepatic and/or extrahepatic insulin clearance. Hepatic and extrahepatic insulin clearance was studied in 31 double incretin receptor knockout (DIRKO) and 45 wild-type (WT) mice, which underwent an Intravenous Glucose Tolerance Test (IVGTT). A novel methodology based on mathematical modeling was designed to provide two sets of values (FEL-P1, CLP-P1, FEL-P2, CLP-P2) accounting for hepatic and extrahepatic clearance in the IVGTT first and second phases, respectively, plus the respective total clearances, CLT-P1 and CLT-P2. A statistically significant difference between DIRKO and WT was found in CLT-P1 (0.61 [0.48–0.82] vs. 0.51 [0.46–0.65] (median [interquartile range]), p = 0.02), which was reflected in the peripheral component, CLP-P1 (0.18 [0.13–0.27] vs. 0.15 [0.11–0.22], p = 0.04), but not in the hepatic component, FEL-P1 (29.7 [26.7–34.9] vs. 28.9 [25.7–32.0], p = 0.18). No difference was detected between DIRKO and WT in CLT-P2 (1.38 [1.13–1.75] vs. 1.69 [1.48–1.87], p = 0.10), neither in CLP-P2 (0.72 [0.64–0.81] vs. 0.79 [0.69–0.87], p = 0.27) nor in FEL-P2 (37.8 [35.1–43.1] vs. 39.8 [35.8–44.2], p = 0.46). In conclusion, our findings suggest that the higher insulin clearance observed in DIRKO compared with WT during the IVGTT first phase may be due to its extrahepatic component.

Aim: Dipeptidyl peptidase-4 (DPP-4) inhibition has effects on both fasting and postprandial glucose. However, the extent of this effect over the whole day and whether different DPP-4 inhibitors have the same effects have not been established. We therefore explored the whole day effects of three different DPP-4 inhibitors versus placebo on glucose, islet and incretin hormones after ingestion of breakfast, lunch and dinner in subjects with metformin-treated and well-controlled type 2 diabetes. Methods: The study was single-centre and crossover designed, involving 24 subjects [12 men, 12 women, mean age 63 years, body mass index 31.0 kg/m2, glycated haemoglobin 44.7 mmol/mol (6.2%)], who underwent four test days in random order. Each whole day test included ingestion of standardized breakfast (525 kcal), lunch (780 kcal) and dinner (560 kcal) after intake of sitagliptin (100 mg) or vildagliptin (50 mg twice), or saxagliptin (5 mg) or placebo. Results: Compared with placebo, DPP-4 inhibition reduced glucose levels, increased beta-cell function (insulin secretory rate in relation to glucose), suppressed glucagon, increased intact glucagon-like-peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) but suppressed total GLP-1 and GIP after all three meals. The effects were sustained throughout the daytime period with similar changes after each meal and did not differ between the DPP-4 inhibitors. Conclusions: DPP-4 inhibition has persistent daytime effects on glucose, islet and incretin hormones with no difference between three different DPP-4 inhibitors. (Less)

OBJECTIVE In type 2 diabetes, insulin resistance and progressive β-cell failure require treatment with high insulin doses, leading to weight gain. Our aim was to study whether a three-meal diet (3Mdiet) with a carbohydrate-rich breakfast may upregulate clock gene expression and, as a result, allow dose reduction of insulin, leading to weight loss and better glycemic control compared with an isocaloric six-meal diet (6Mdiet). RESEARCH DESIGN AND METHODS Twenty-eight volunteers with diabetes (BMI 32.4 ± 5.2 kg/m2 and HbA1c 8.1 ± 1.1% [64.5 ± 11.9 mmol/mol]) were randomly assigned to 3Mdiet or 6Mdiet. Body weight, glycemic control, continuous glucose monitoring (CGM), appetite, and clock gene expression were assessed at baseline, after 2 weeks, and after 12 weeks. RESULTS 3Mdiet, but not 6Mdiet, led to a significant weight loss (−5.4 ± 0.9 kg) (P < 0.01) and decreased HbA1c (−12 mmol/mol [−1.2%]) (P < 0.0001) after 12 weeks. Fasting glucose and daily and nocturnal glucose levels were significantly lower on the 3Mdiet. CGM showed a significant decrease in the time spent in hyperglycemia only on the 3Mdiet. Total daily insulin dose was significantly reduced by 26 ± 7 units only on the 3Mdiet. There was a significant decrease in the hunger and cravings only in the 3Mdiet group. Clock genes exhibited oscillation, increased expression, and higher amplitude on the 3Mdiet compared with the 6Mdiet. CONCLUSIONS A 3Mdiet, in contrast to an isocaloric 6Mdiet, leads to weight loss and significant reduction in HbA1c, appetite, and overall glycemia, with a decrease in daily insulin. Upregulation of clock genes seen in this diet intervention could contribute to the improved glucose metabolism.

Aim Use of the glucagon-like peptide 1 receptor agonist liraglutide has been shown to reduce weight. Different types of anthropometric measurements can be used to measure adiposity. This study evaluated the effect of liraglutide on sagittal abdominal diameter, waist circumference, waist-to-hip ratio and adiponectin levels in people with type 2 diabetes (T2D) treated with multiple daily insulin injections (MDI). Materials and methods In the multicentre, double-blind, placebo-controlled MDI-liraglutide trial, 124 individuals with T2D treated with MDI were randomized to either liraglutide or placebo. Basal values of weight, waist circumference, waist-to-hip ratio, sagittal abdominal diameter and adiponectin were compared with measurements at 12 and 24 weeks after randomization. Results Baseline-adjusted mean weight loss was 3.8 +/- 2.9 kg greater in liraglutide than placebo-treated individuals (p < 0.0001). Waist circumference was reduced by 2.9 +/- 4.3 cm and 0.2 +/- 3.6 cm in the liraglutide and placebo groups, respectively, after 24 weeks (baseline-adjusted mean difference: 2.6 +/- 4.0 cm, p = 0.0005). Corresponding reductions in sagittal abdominal diameter were 1.1 +/- 1.7 cm and 0.0 +/- 1.8 cm (baseline-adjusted mean difference: 1.1 +/- 1.7 cm, p = 0.0008). Hip circumference was reduced in patients randomized to liraglutide (baseline-adjusted mean difference between treatment groups: 2.8 +/- 3.8 cm, p = 0.0001), but there was no significant difference between the groups in either waist-to-hip ratio (baseline-adjusted mean difference: 0.0 +/- 0.04 cm, p = 0.51) or adiponectin levels (baseline-adjusted mean difference: 0.8 +/- 3.3 mg L-1, p = 0.17). Lower HbA1c and mean glucose levels measured by masked continuous glucose monitoring at baseline were associated with greater effects of liraglutide on reductions in waist circumference and sagittal abdominal diameter. Conclusions In patients with T2D, adding liraglutide to MDI may reduce abdominal and hip obesity to a similar extent, suggesting an effect on both visceral and subcutaneous fat. Liraglutide had greater effects on reducing abdominal obesity in patients with less pronounced long-term hyperglycaemia but did not affect adiponectin levels.

Whey protein (WP), found in dairy products, is rich in branched chain amino acids and bioactive peptides that stimulate the secretion of incretin hormones and insulin, but has typically required relatively high caloric doses. Technologies enhancing absorption could enable use of a lower WP-dose. This single-intervention study in type 2 diabetes (drug-naive or on metformin), evaluated the effects of 10g WP (40 Cal) prepared with novel micelle-technology [WPM], or placebo (PBO, 0 Cal), taken as a 125 mL shot 15 min ahead of a pizza meal (622 Cal). PP glucose (0-4h) and intact GLP-1 (0-2h) responses were assessed in blood. Twenty-six individuals (mean age 62 years, baseline HbA1c 7,5%, BMI 29.1 kg/m2) completed both sequences. Compared to PBO, pre-meal WPM significantly altered the early PP glucose trajectory (Fig), reducing the 2h incremental area under the curve (iAUC) by 22% (mean [95% CI] difference iAUC-30-120min -29.43 [-55.45, -3.40] mg/dLxh, p=0.0283). The iAUC-30-180min was similar (-31.58 [-68.43, 5.26], p=0.0896). A 66.1% increase in GLP-1 iAUC-30-120min was observed (4.80 [2.19, 7.40], p=0.0009). Compared to PBO, 10g WPM taken 15 min before a pizza meal, significantly reduced the early glycemic burden and significantly augmented the GLP-1 response, suggesting its use as a convenient pre-meal shot to improve PP metabolic profile in type 2 diabetes. Disclosure L. H. De gregorio: Research Support; Self; Nestle, Novartis Pharmaceuticals Corporation. O. E. Johansen: Employee; Self; Boehringer Ingelheim International GmbH, Nestle. I. Neeland: Consultant; Self; Merck & Co., Inc. R. Zagury: Board Member; Self; Abbott, Consultant; Self; Nestle, Speaker’s Bureau; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Danone Nutricia, Novo Nordisk Pharma Ltd., Sanofi, Servier Laboratories. B. Ahren: Stock/Shareholder; Self; AstraZeneca, Novo Nordisk Inc. J. M. Neutel: None. K. Reyes: Employee; Self; Nestle. E. Perrin: Other Relationship; Self; Nestle. E. Berk: Employee; Self; Nestle Health Science. M. Von eynatten: Employee; Self; Nestle. Funding Nestle Health Science

Glucagon is secreted from the pancreatic alpha cells and plays an important role in the maintenance of glucose homeostasis, by interacting with insulin. The plasma glucose levels determine whether glucagon secretion or insulin secretion is activated or inhibited. Despite its relevance, some aspects of glucagon secretion and kinetics remain unclear. To gain insight into this, we aimed to develop a mathematical model of the glucagon kinetics during an oral glucose tolerance test, which is sufficiently simple to be used in the clinical practice. The proposed model included two first-order differential equations -one describing glucagon and the other describing C-peptide in a compartment remote from plasma - and yielded a parameter of possible clinical relevance (i.e., SGLUCA(t), glucagon-inhibition sensitivity to glucose-induced insulin secretion). Model was validated on mean glucagon data derived from the scientific literature, yielding values for SGLUCA(t) ranging from -15.03 to 2.75 (ng of glucagon·nmol of C-peptide-1). A further validation on a total of 100 virtual subjects provided reliable results (mean residuals between -1.5 and 1.5 ng·L-1) and a negative significant linear correlation (r = -0.74, p < 0.0001, 95% CI: -0.82 – -0.64) between SGLUCA(t) and the ratio between the areas under the curve of suprabasal remote C-peptide and glucagon. Model reliability was also proven by the ability to capture different patterns in glucagon kinetics. In conclusion, the proposed model reliably reproduces glucagon kinetics and is characterized by sufficient simplicity to be possibly used in the clinical practice, for the estimation in the single individual of some glucagon-related parameters.

Summary Background Omission of breakfast results in higher glucose and lower insulin and incretin hormone levels after both lunch and dinner. Whether omission of lunch has a similar impact on the following meal is not known. Aim This study therefore explored whether omission of lunch ingestion affects glucose, islet and incretin hormones after dinner ingestion in healthy subjects. Materials & Methods Twelve male volunteers (mean age 22 years, BMI 22.5 kg/m2) underwent two test days in random order with standard breakfast and dinner on both days with provision or omission of standard lunch in between. Results The results showed that throughout the 300 minutes study period, glucose, insulin, glucagon and GIP levels after dinner ingestion did not differ between the two tests. In contrast, C‐peptide, and GLP‐1 levels were 26%‐35% higher at later time points after dinner ingestion when lunch had been omitted (P, This study explored whether omission of lunch ingestion affects glucose, islet and incretin hormones after dinner ingestion in healthy subjects. Twelve male volunteers underwent two test days in random order with standard breakfast and dinner on both days with provision or omission of standard lunch in between. The results showed that omission of lunch increases GLP‐1 and insulin secretion and possibly also insulin clearance resulting in unchanged glucose and insulin levels after dinner ingestion.

Aims: To assess the effect of baseline body mass index (BMI) and the occurrence of nausea and/or vomiting on weight loss induced by semalgutide, a once-weekly glucagon-like peptide 1 analogue for the treatment of type 2 diabetes. Semaglutide demonstrated superior reductions in HbA1c and superior weight loss (by 2.3-6.3 kg) versus different comparators across the SUSTAIN 1 to 5 trials; the contributing factors to weight loss are not established. Materials and Methods: Subjects with inadequately controlled type 2 diabetes (drug-naive or on background treatment) were randomized to subcutaneous semaglutide 0.5 mg (excluding SUSTAIN 3), 1.0 mg (all trials), or comparator (placebo, sitagliptin, exenatide extended release or insulin glargine). Subjects were subdivided by baseline BMI and reporting (yes/no) of any nausea and/or vomiting. Change from baseline in body weight was assessed within each trial and subgroup. A mediation analysis separated weight loss into direct or indirect (mediated by nausea or vomiting) effects. Results: Clinically relevant weight-loss differences were observed across all BMI subgroups, with a trend towards higher absolute weight loss with higher baseline BMI. Overall, 15.2% to 24.0% and 21.5% to 27.2% of subjects experienced nausea or vomiting with semaglutide 0.5 and 1.0 mg, respectively, versus 6.0% to 14.1% with comparators. Only 0.07 to 0.5 kg of the treatment difference between semaglutide and comparators was mediated by nausea or vomiting (indirect effects). Conclusions: In SUSTAIN 1 to 5, semaglutide-induced weight loss was consistently greater versus comparators, regardless of baseline BMI. The contribution of nausea or vomiting to this weight loss was minor. (Less)

To explore the effects of a single dose of the DPP-4 inhibitor sitagliptin on glucose-standardized insulin secretion and β-cell glucose sensitivity after meal ingestion, 12 healthy and 12 drug-naive, well-controlled type 2 diabetes (T2D) subjects (mean HbA1c 43mmol/mol, 6.2%) received sitagliptin (100mg) or placebo before a meal (525kcal). β-cell function was measured as the insulin secretory rate at a standardized glucose concentration and the β-cell glucose sensitivity (the slope between glucose and insulin secretory rate). Incretin levels were also monitored. Sitagliptin increased standardized insulin secretion, in both healthy and T2D subjects, compared to placebo, but without increasing β-cell glucose sensitivity. Sitagliptin also increased active glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) and reduced total (reflecting the secretion) GIP, but not total GLP-1 levels. We conclude that a single dose of DPP-4 inhibition induces dissociated effects on different aspects of β-cell function and incretin hormones after meal ingestion in both healthy and well-controlled T2D subjects. (Less)

The incretin glucagon-like peptide-1 (GLP-1) is a gut hormone but also locally produced in pancreatic islets. We evaluated effects of GLP-1 on the insulin response to a gradual increase in glucose in mice within physiological levels. We initially developed a glucose ramp technique in mice. Glucose levels were slowly increased by 0.2 mmol/l/min for 40 min under control conditions, during intravenous infusion of GLP-1 and in GLP-1 receptor knockout mice. In control mice, glucose levels increased from 8.5 ± 0.3 to 16.1 ± 0.3 mmol/l over the 40 min, i.e., by 0.22 ± 0.01 mmol/l/min. This resulted in a slow increase in insulin levels by 96 ± 38 pmol/l from the baseline of 319 ± 53 pmol/l. GLP-1 at 0.5 nmol/kg as bolus plus 0.3 nmol/kg/min over 40 min progressively increased this insulin response by 100-fold, to 9.5 ± 0.2 nmol/l (P < 0.001). Higher doses of GLP-1 enhanced the insulin response similarly (1.0 or 3.0 nmol/kg bolus followed by 0.4 or 1.2 nmol/kg/min), whereas a lower dose (0.3 nmol/kg bolus plus 0.15 nmol/kg/min) had no significant effect compared to controls. Moreover, there was no significant difference in insulin responses between controls and GLP-1 receptor knockout mice. Since the increase in glucose levels were standardized, there was no significant difference in glucose levels between the experimental groups. We conclude that the glucose ramp technique is a tool for studies on insulin responses to slow changes in circulating glucose levels in mice. We also conclude that GLP-1 is extraordinarily potent in enhancing the insulin response to a slow increase in glucose levels.

Acute studies show that addition of whey protein at breakfast has a glucose-lowering effect through increased incretin and insulin secretion. However, whether this is a long-term effect in Type 2 diabetes is unknown. Fifty-six Type 2 diabetes participants aged 58.9±4.5 years, BMI 32.1±0.9 kg/m2 and HbA1C 7.8±0.1% (61.6±0.79 mmol/mol) were randomized to one of 3 isocaloric diets with similar lunch and dinner, but different breakfast: 1) 42 g total protein, 28 g whey (WBdiet, n=19); 2) 42 g various protein sources (PBdiet, n=19); or 3) high-carbohydrate breakfast, 17 g protein from various sources (CBdiet, n=18). Body weight and HbA1C were examined after 12 weeks. All participants underwent three all-day meal challenges for postprandial glycemia, insulin, C-peptide, intact glucagon-like peptide 1 (iGLP-1), ghrelin and hunger and satiety scores. Overall postprandial AUCglucose was reduced by 12% in PBdiet and by 19% in WBdiet, compared with CBdiet (P

Aims Diabetes therapies that provide durable glycaemic control for people with type 2 diabetes mellitus (T2DM) are needed. We present efficacy results of albiglutide, a glucagon-like peptide-1 receptor agonist, in people with T2DM over a 3-year period. Methods Five of the 8 HARMONY phase 3 trials, comparing albiglutide with other therapies or placebo across a spectrum of clinical care, lasted for a preplanned 3 years. Participants with uncontrolled hyperglycaemia who met predetermined criteria could receive rescue medication. The ability to remain on study medication without needing additional rescue was an efficacy measure. Glycaemic measures and body weight were analysed in 2 populations: those who remained rescue-free and all participants. Results Participants ( n = 3132) were randomised to albiglutide or comparator. A greater proportion of participants who received albiglutide remained rescue-free (55–71%) compared with placebo (35–51%; p p = 0.002). The proportion of rescue-free participants with albiglutide did not differ from glimepiride or insulin glargine, was higher than with sitagliptin ( p = 0.013), and lower than with pioglitazone ( p = 0.045). At 3 years, albiglutide was associated with clinically significant reductions in hyperglycaemia (eg, rescue-free participants: HbA1c −0.52% [SE0.11] to −0.98% [0.12]; −5.7 mmol/mol [1.2] to −10.7 mmol/mol [1.3] and all participants: HbA1c −0.29% [0.11] to − 0.92% [0.13]; −3.2 mmol/mol [1.2] to −10.1 mmol/mol [1.4]). Albiglutide was also associated with modest reductions in body weight vs pioglitazone, glimepiride, and insulin glargine, which were associated with weight gain. Conclusion These 3-year efficacy data support long-term use of albiglutide in the management of people with T2DM. ClinicalTrials.gov NCT00849056 , NCT00849017 , NCT00838903 , NCT00838916 , NCT00839527 .

OBJECTIVE The circadian clock regulates glucose metabolism by mediating the activity of metabolic enzymes, hormones, and transport systems. Breakfast skipping and night eating have been associated with high HbA1c and postprandial hyperglycemia after lunch and dinner. Our aim was to explore the acute effect of breakfast consumption or omission on glucose homeostasis and clock gene expression in healthy individuals and individuals with type 2 diabetes. RESEARCH DESIGN AND METHODS In a crossover design, 18 healthy volunteers and 18 volunteers with 14.5 ± 1.5 years diabetes, BMI 30.7 ± 1.1 kg/m2, and HbA1c 7.6 ± 0.1% (59.6 ± 0.8 mmol/mol) were randomly assigned to a test day with breakfast and lunch (YesB) and a test day with only lunch (NoB). Postprandial clock and clock-controlled gene expression, plasma glucose, insulin, intact glucagon-like peptide 1 (iGLP-1), and dipeptidyl peptidase IV (DPP-IV) plasma activity were assessed after breakfast and lunch. RESULTS In healthy individuals, the expression level of Per1, Cry1, Rorα, and Sirt1 was lower (P < 0.05) but Clock was higher (P < 0.05) after breakfast. In contrast, in individuals with type 2 diabetes, Per1, Per2, and Sirt1 only slightly, but significantly, decreased and Rorα increased (P < 0.05) after breakfast. In healthy individuals, the expression level of Bmal1, Rorα, and Sirt1 was higher (P < 0.05) after lunch on YesB day, whereas the other clock genes remained unchanged. In individuals with type 2 diabetes, Bmal1, Per1, Per2, Rev-erbα, and Ampk increased (P < 0.05) after lunch on the YesB day. Omission of breakfast altered clock and metabolic gene expression in both healthy and individuals with type 2 diabetes. CONCLUSIONS Breakfast consumption acutely affects clock and clock-controlled gene expression leading to normal oscillation. Breakfast skipping adversely affects clock and clock-controlled gene expression and is correlated with increased postprandial glycemic response in both healthy individuals and individuals with diabetes.

Aims Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) stimulate the incretin system and lower glycaemic parameters in type 2 diabetes mellitus (T2DM). This analysis of clinical studies of up to 3 years evaluated the safety of albiglutide, a GLP-1 RA, in people with T2DM. Methods Integrated safety analysis included seven phase-3 T2DM studies of albiglutide compared with placebo and/or active comparators (a dipeptidyl peptidase-4 inhibitor, GLP-1 RA, insulin, sulphonylurea, and thiazolidinedione). Results Studies of 32 months (HARMONY 7), 1 year (HARMONY 6), and 3 years (HARMONY 1–5), reported similar rates of adverse events (AEs) (84.8%, 82.3%), and serious AEs (13.1%, 12.9%) between albiglutide and all comparators, respectively. AEs that did not differ between the groups included symptomatic or severe hypoglycaemia as well as nausea (12.0%, 11.3%) and vomiting (5.3%, 4.7%) for albiglutide and all comparators, respectively. According to the Medical Dictionary for Regulatory Activities preferred terms, only diarrhoea (13.7%, 9.9%), injection-site reaction (9.0%, 2.0%), and peripheral oedema (4.5%, 6.8%) had at least 2% difference between the albiglutide and all-comparator groups. In a similar integrated analysis, pancreatitis occurred more often with albiglutide (0.3%, 0.1%). Renal and cardiac function did not differ between the two groups. Conclusions In an integrated analysis of seven phase 3 clinical trials, albiglutide-treated patients experienced frequencies of AEs (including cardiovascular and renal) similar to the all-comparators group treated with other T2DM medications or placebo. Albiglutide treatment was associated with higher rates of diarrhoea and injection-site reactions, but not increased nausea and vomiting, versus all comparators.

Introduction The effects of the GLP-1 analogue liraglutide on time in hypoglycaemia, time in hyperglycaemia, and time in range for type 2 diabetes patients initially treated with multiple daily insulin injections (MDI) were investigated. Variables associated with hypoglycaemia in the current population were also identified. Methods Analyses were based on data from a previously performed double-blind, placebo-controlled trial in which 124 MDI-treated patients with type 2 diabetes were randomized to liraglutide or placebo. Masked continuous glucose monitoring (CGM) was performed at baseline and week 24 in 99 participants. Results The mean time in hypoglycaemia was similar for participants receiving liraglutide and those receiving placebo after 24 weeks of treatment. Mean time in target was greater in the liraglutide group than in the placebo group: 430 versus 244 min/24 h (p 10 mmol/l and > 14 mmol/l, respectively. Lower mean glucose level, lower C-peptide, and higher glucose variability were associated with an increased risk of hypoglycaemia in both treatment groups. Higher proinsulin level was associated with a lower risk of hypoglycaemia in the liraglutide group. Conclusion For type 2 diabetes patients initially treated with MDI, introducing liraglutide had a beneficial effect on glucose profiles estimated by masked CGM. Mean glucose level, glycaemic variability, C-peptide, and proinsulin level influenced the risk of hypoglycaemia in this population. Trial Registration ClinicalTrials.gov, number (EudraCT nr: 2012-001941-42). Funding Novo Nordisk funded this study. The Diabetes Research Unit, NU-Hospital Group funded the journal’s Rapid Service Fee. Electronic Supplementary Material The online version of this article (10.1007/s13300-019-00692-1) contains supplementary material, which is available to authorized users.

Hypoglycaemia is common in both type 1 and type 2 diabetes and has both acute and long-term consequences. Therefore, a key to proper glucose-lowering therapy in diabetes is to avoid or prevent hypoglycaemia. Incretin therapy (DPP-4 inhibitors and GLP-1 receptor agonists) offers an advantage in this respect, because it reduces glucose with a low risk of hypoglycaemia, both in monotherapy and in combination with other therapies. The reason for this low risk of hypoglycaemia is the glucose dependency of action of incretin therapy and the sustainment of glucose counter-regulatory hormone responses to hypoglycaemia, in particular the glucagon response. Incretin therapy is also associated with a low risk of hypoglycaemia in patient groups which are especially vulnerable and susceptible for hypoglycaemia, e.g., subjects with renal impairment, elderly subjects and subjects with on-going insulin therapy. This review summarizes how incretin therapy may meet the challenges of hypoglycaemia and suggests that incretin therapy is a therapy of choice to avoid hypoglycaemia, both in the general diabetes population and in subjects with increased risk or vulnerability for hypoglycaemia.

To study whether activation of GLP-1 receptors importantly contributes to the insulinotropic action of exogenously administered glucagon, we have performed whole animal experiments in normal mice and in mice with GLP-1 receptor knockout. Glucagon (1, 3 or 10 μg/kg), the GLP-1 receptor antagonist exendin 9-39 (30 nmol/kg), glucose (0.35 g/kg) or the incretin hormone glucose-dependent insulinotropic polypeptide (GIP; 3 nmol/kg) was injected intravenously or glucose (75 mg) was given orally through gavage. Furthermore, islets were isolated and incubated in the presence of glucose with or without glucagon. It was found that the insulin response to intravenous glucagon was preserved in GLP-1 receptor knockout mice but that glucagon-induced insulin secretion was markedly suppressed in islets from GLP-1 receptor knockout mice. Similarly, the GLP-1 receptor antagonist markedly suppressed glucagon-induced insulin secretion in wildtype mice. These data suggest that GLP-1 receptors contribute to the insulinotropic action of glucagon and that there is a compensatory mechanism in GLP-1 receptor knockout mice that counteracts a reduced effect of glucagon. Two potential compensatory mechanisms (glucose and GIP) were explored. However, neither of these seemed to explain why the insulin response to glucagon is not suppressed in GLP-1 receptor knockout mice. Based on these data we confirm the hypothesis that glucagon-induced insulin secretion is partially mediated by GLP-1 receptors on the beta cells and we propose that a compensatory mechanism, the nature of which remains to be established, is induced in GLP-1 receptor knockout mice to counteract the expected impaired insulin response to glucagon in these mice.

Dipeptidyl peptidase 4 (DPP-4) inhibitors are now being clinically utilized as glucose-lowering medications for the treatment of type 2 diabetes. Their widespread use and effective glucose-lowering properties have led to great interest in the mechanism of action of this class of drug. Although it has been well accepted that DPP-4 inhibitors lower glucose in part by increasing postprandial insulin secretion and suppressing fasting and postprandial hyperglucagonemia, recent studies have suggested that DPP-4 inhibition has other metabolically beneficial properties that are extrapancreatic in nature. This review explores the changes in DPP-4 expression and activity in metabolic disease states and discusses the metabolic consequences of DPP-4 inhibition on a systemic and tissue-specific basis. It concludes that there is considerable scientific evidence and a growing body of clinical evidence to suggest that DPP-4 inhibition would be beneficial in a number of metabolic disorders in addition to type 2 diabetes. (Less)

Hyperinsulinemia is an adaptive mechanism that enables the maintenance of normoglycemia in the presence of insulin resistance. We assessed whether glucagon is also involved in the adaptation to insulin resistance. A total of 1,437 individuals underwent an oral glucose tolerance test with measurements of circulating glucose, insulin, and glucagon concentrations at 0, 30 and 120 min. Early glucagon suppression was defined as suppression in the period from 0 to 30 min, and late glucagon suppression as 30 to 120 min after glucose intake. Insulin sensitivity was estimated by the validated insulin sensitivity index. Individuals with screen-detected diabetes had 30% higher fasting glucagon levels and diminished early glucagon suppression, but greater late glucagon suppression when compared with individuals with normal glucose tolerance (P ≤ 0.014). Higher insulin resistance was associated with higher fasting glucagon levels, less early glucagon suppression, and greater late glucagon suppression (P < 0.001). The relationship between insulin sensitivity and fasting glucagon concentrations was nonlinear (P < 0.001). In conclusion, increased fasting glucagon levels and delayed glucagon suppression, together with increased circulating insulin levels, develop in parallel with insulin resistance. Therefore, glucose maintenance during insulin resistance may depend not only on hyperinsulinemia but also on the ability to suppress glucagon early after glucose intake.

It is not known whether GIP receptor and GLP-1 receptor knockout (KO) mice have perturbations in glucagon secretion or insulin clearance, and studies on impact on fasting glycemia have previously been inconsistent in these mice. We therefore studied glucagon secretion after oral whey protein (60 mg) and intravenous arginine (6.25 mg), insulin clearance after intravenous glucose (0.35 g/kg) and fasting glucose, insulin, and glucagon levels after standardized 5-h fasting in female GIP receptor and GLP-1 receptor KO mice and their wild-type (WT) littermates. Compared with WT controls, GIP receptor KO mice had normal glucagon responses to oral protein and intravenous arginine, except for an enhanced 1-min response to arginine, whereas glucagon levels after oral protein and intravenous arginine were enhanced in GLP-1 receptor KO mice. Furthermore, the intravenous glucose test revealed normal insulin clearance in both GIP receptor and GLP-1 receptor KO mice, whereas β-cell glucose sensitivity was enhanced in GIP receptor KO mice and reduced in GLP-1 receptor KO mice. Finally, GIP receptor KO mice had reduced fasting glucose (6.7 ± 0.1, n = 56, vs. 7.4 ± 0.1 mmol/l, n = 59, P = 0.001), whereas GLP-1 receptor KO mice had increased fasting glucose (9.1 ± 0.2, n = 44, vs. 7.7 ± 0.1 mmol/l, n = 41, P < 0.001). We therefore suggest that GIP has a limited role for glucagon secretion in mice, whereas GLP-1 is of importance for glucagon regulation, that GIP and GLP-1 are of importance for the regulation of β-cell function beyond their role as incretin hormones, and that they are both of importance for fasting glucose.

Today, glucagon‐like peptide‐1 (GLP‐1) receptor agonists are established glucose‐lowering drugs used in the management of type 2 diabetes. Their development emerged from the understanding that a combined islet dysfunction comprising of impaired insulin secretion and exaggerated glucagon secretion is the key defect of hyperglycemia. GLP‐1 was shown to target these defects, and after the discovery that dipeptidyl peptidase‐4 inactivates native GLP‐1, several different dipeptidyl peptidase‐4‐resistant GLP‐1 receptor agonists have been developed. They are administered subcutaneously, but show differences in molecular structure, molecular size and pharmacokinetics, the latter allowing twice‐daily, once‐daily or once‐weekly administration. They have been shown to be efficient in reducing both glycated hemoglobin and bodyweight, and to be safe and highly tolerable. Cardiovascular outcomes trials have shown them to be neutral or beneficial. GLP‐1 receptor agonists are positioned as add‐ons to metformin alone or in combination with oral agents in the clinical paradigm. They are also efficient when combined with insulin, and fixed dose combinations with long‐acting insulin have been developed. Recent development includes a very long administration schedule and oral availability. The research from the first demonstration of the antidiabetic action of GLP‐1 in the early 1990s to the enormously accumulated data today represents a successful and rational development, which has been characterized by focused perseverance to establish this therapy in the management of type 2 diabetes.

Aims: Maintainance of glucagon response to hypoglycaemia is important as a safeguard against hypoglycaemia during glucose-lowering therapy in type 2 diabetes. During recent years, DPP-4 (dipeptidyl peptidase-4) inhibition has become more commonly used in elderly patients. However, whether DPP-4 inhibition affects the glucagon response to hypoglycaemia in the elderly is not known and was the aim of this study. Methods: In a single-centre, double-blind, randomized, placebo-controlled crossover study, 28 subjects with metformin-treated type 2 diabetes (17 male, 11 female; mean age, 74years [range 65-86]; mean HbA1c, 51.5mmol/mol [6.9%]) received sitagliptin (100mg once daily) as add-on therapy or placebo for 4weeks with a 4-week washout period in between. After each treatment period, the subjects underwent a standard breakfast test, followed by a 2-step hyperinsulinaemic hypoglycaemic clamp (target 3.5 and 3.0mmol/L), followed by lunch. Results: Glucagon levels after breakfast and lunch, and the glucagon response at 3.5mmol/L, were lower after sitagliptin than after placebo. However, the glucagon response to hypoglycaemia at 3.1mmol/L did not differ significantly between the two. Similarly, the noradrenaline, adrenaline and cortisol responses were lower with sitagliptin than with placebo at 3.5mmol/L, but not at 3.1mmol/L glucose. Responses in pancreatic polypeptide did not differ between the two. Conclusions: Elderly subjects with metformin-treated type 2 diabetes have lower glucagon levels at 3.5mmol/L glucose, but maintain the glucagon response to hypoglycaemia at 3.1mmol/L during DPP-4 inhibition, which safeguards against hypoglycaemia and may contribute to decreasing the risk of hypoglycaemia by DPP-4 inhibition in this age group. (Less)

To establish whether incretin hormones affect insulin clearance, the aim of this study was to assess insulin clearance in mice with genetic deletion of receptors for both glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), so called double incretin receptor knockout mice (DIRKO). DIRKO ( n = 31) and wild-type (WT) C57BL6J mice ( n = 45) were intravenously injected with d-glucose (0.35 g/kg). Blood was sampled for 50 min and assayed for glucose, insulin, and C-peptide. Data were modeled to calculate insulin clearance; C-peptide kinetics was established after human C-peptide injection. Assessment of C-peptide kinetics revealed that C-peptide clearance was 1.66 ± 0.10 10−3 1/min. After intravenous glucose administration, insulin clearance during first phase insulin secretion was markedly higher in DIRKO than in WT mice (0.68 ± 0.06 10−3 l/min in DIRKO mice vs. 0.54 ± 0.03 10−3 1/min in WT mice, P = 0.02). In contrast, there was no difference between the two groups in insulin clearance during second phase insulin secretion ( P = 0.18). In conclusion, this study evaluated C-peptide kinetics in the mouse and exploited a mathematical model to estimate insulin clearance. Results showed that DIRKO mice have higher insulin clearance than WT mice, following intravenous injection of glucose. This suggests that incretin hormones reduce insulin clearance at physiological, nonstimulated levels.

Aims: Previous studies have shown that dipeptidyl peptidase (DPP)-4 inhibition lowers glucagon levels whereas sodium-glucose co-transporter 2 (SGLT-2) inhibition increases them. This study evaluated the extent of these opposite effects in a direct comparative head-to-head study. Methods: In a single-centre, randomized study with a cross-over design, 28 metformin-treated patients with type 2 diabetes (T2D) (mean age, 63 years; baseline HbA1c, 6.8%) were treated with vildagliptin (50 mg twice daily) or dapagliflozin (10 mg once daily) for 2 weeks, with a 4-week wash-out period between the two separate treatments. After each treatment period, a meal test was undertaken, with measurements of islet and incretin hormones and 4-hour area under the curve (AUC) levels were estimated. Results: Fasting glucagon (35.6 ± 2.5 vs 39.4 ± 3.4 pmoL/L; P = .032) and postprandial glucagon (4-hour AUCglucagon, 32.1 ± 2.3 vs 37.5 ± 2.7 nmoL/L min; P = .001) were ~15% lower after vildagliptin compared to dapagliflozin treatment. This was associated with stronger early (15 minute) C-peptide response and higher 4-hour AUCC-peptide (P < .010), higher 4-hour AUC of the intact form of glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) (P < .001) and lower 4-hour AUC of total GIP and GLP-1 (P < .001). Conclusion: Treatment with DPP-4 inhibition with vildagliptin results in 15% lower fasting and postprandial glucagon levels compared to SGLT-2 inhibition with dapagliflozin. DPP-4 inhibition also induces more rapid insulin secretion and higher levels of intact incretin hormones, resulting in stronger feedback inhibition of incretin hormone secretion than SGLT-2 inhibition. (Less)

It has been reported that the incretin system, including regulated GLP-1 secretion and locally expressed DPP-4, is present in pancreatic islets. In this study we comprehensively evaluated the expression and role of DPP-4 in islet alpha and beta cells from non-diabetic (ND) and type 2 diabetic (T2D) individuals, including the effects of its inhibition on beta cell function and survival. Isolated islets were prepared from 25 ND and 18 T2D organ donors; studies were also performed with the human insulin-producing EndoC-βH1 cells. Morphological (including confocal microscopy), ultrastructural (electron microscopy, EM), functional (glucose-stimulated insulin secretion), survival (EM and nuclear dyes) and molecular (RNAseq, qPCR and western blot) studies were performed under several different experimental conditions. DPP-4 co-localized with glucagon and was also expressed in human islet insulin-containing cells. Furthermore, DPP-4 was expressed in EndoC-βH1 cells. The proportions of DPP-4 positive alpha and beta cells and DPP-4 gene expression were significantly lower in T2D islets. A DPP-4 inhibitor protected ND human beta cells and EndoC-βH1 cells against cytokine-induced toxicity, which was at least in part independent from GLP1 and associated with reduced NFKB1 expression. Finally, DPP-4 inhibition augmented glucose-stimulated insulin secretion, reduced apoptosis and improved ultrastructure in T2D beta cells. These results demonstrate the presence of DPP-4 in human islet alpha and beta cells, with reduced expression in T2D islets, and show that DPP-4 inhibition has beneficial effects on human ND and T2D beta cells. This suggests that DPP-4, besides playing a role in incretin effects, directly affects beta cell function and survival.