GLP-1 Receptor Agonists Induce Growth Hormone Secretion in Healthy Volunteers.

INTRODUCTION: Growth hormone (GH) is an essential regulator of growth, body composition and fuel metabolism and, consequently, GH secretion is under the feedback control of numerous nutritional and endocrine mediators. Glucagon-like peptide 1 receptor agonists (GLP-1RAs) have been shown to exert pleiotropic effects, including stimulation of the activity of the hypothalamic-pituitary-adrenal axis. As GLP-1RAs exert multiple metabolic effects, we hypothesised that they may also affect the secretion of GH and examined the effect of a short-acting and a long-acting GLP-1 RA on GH secretion. METHODS: This is a post hoc analysis of data from clinical trials. Two separate single-group open-label clinical trials were carried out in the ambulatory care setting with a duration of 1 and 21 days, respectively. Healthy adult male and female volunteers with no chronic illnesses or use of daily medicines were recruited for the study. The two interventions were: study 1, single dose of 10 µg exenatide administered subcutaneously (s.c.); study 2, 0.6 mg liraglutide administered s.c. once daily for 21 days. RESULTS: Administration of a single dose of exenatide (study 1) caused a clear increase in GH levels, peaking between 60 and 120 min post-administration. There was also a small but statistically significant decrease in luteinising hormone and testosterone levels 120 min after exenatide dosing. Administration of the long-acting GLP-1RA liraglutide daily for 21 days (study 2) elicited an increase in GH levels with no change in insulin-like growth factor-1 (IGF-1) concentrations after 3 weeks of treatment. CONCLUSIONS: The results show that the administration of GLP-1RAs may elicit an increase in growth hormone levels. GLP-1 signalling may be a novel mechanism of regulation of GH secretion. This finding needs to be replicated in the placebo-controlled trial. CLINICAL TRIAL REGISTRATION NUMBERS: NCT02089256 and NCT03160261.

Systematic review and meta-analysis of head-to-head trials comparing sulfonylureas and low hypoglycaemic risk antidiabetic drugs.

BACKGROUND: Safety of sulfonylurea drugs in the treatment of Type 2 Diabetes is still under debate. The aim of this study was to compare the all-cause mortality and cardiovascular adverse events of sulfonylureas and drugs with a low risk for hypoglycaemia in adults with type 2 diabetes. METHODS: Systematic review and meta-analysis of randomised controlled trials. DATA SOURCES: MEDLINE (PubMed, OVID), Embase, Cochrane Central Register of Controlled Trials, CINAHL, WOS and Lilacs. STUDY SELECTION: Randomised controlled head-to-head trials that compared sulfonylureas with active control with low hypoglycaemic potential in adults (≥ 18 years old) with type 2 diabetes published up to August 2015. The drug classes involved in the analysis were metformin, dipeptidyl peptidase-4 (DPP-4) inhibitors, sodium-glucose co-transporter-2 (SGLT-2) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists. OUTCOMES: The primary endpoint was all-cause mortality. The secondary endpoints were MACE, cardiovascular events and severe hypoglycaemia. SYNTHESIS OF RESULTS: Two reviewers checked study eligibility, independently extracted data and assessed quality with disagreements resolved through discussion. We assessed the risk of bias of the included studies using the Cochrane risk of bias tool for randomized trials v2. Pooled odds ratios (ORs) were estimated by using fixed effects model. The study is registered on PROSPERO (26/05/2016 CRD42016038780). RESULTS: Our final analysis comprised 31 studies (26,204 patients, 11,711 patients given sulfonylureas and 14,493 given comparator drugs). In comparison to drugs with low hypoglycaemic potential, sulfonylureas had higher odds for all-cause mortality (OR 1.32, 95% CI 1.00-1.75), MACE (OR 1.32, 95% CI 1.07-1.61), myocardial infarction (fatal and non-fatal) (OR 1.67, 95% CI 1.17-2.38) and hypoglycaemia (OR 5.24, 95% CI 4.20-6.55). Subsequent sensitivity analysis revealed differences in the effect of sulfonylureas, with an increased risk of all-cause mortality with glipizide but not the other molecules. CONCLUSION: Our meta-analysis raises concern about the safety of SUs compared to alternative drugs involved in current analysis. Important differences may exist within the drug class, and glimepiride seems to have best safety profile.

A GLP-1 Receptor Agonist Inhibits Aldosterone Release in Healthy Volunteers.

Glucagon-like peptide 1 receptor agonists (GLP-1 RAs) are antidiabetic drugs with effects beyond antihyperglycemic action. The aim of the study was to examine whether a single dose of exenatide could be used as a stimulation test for the pituitary-adrenal axis. We carried out a single-group, open-label pilot clinical trial in an ambulatory setting. Ten healthy volunteers of both sexes with body weight>65 kg and age between 18-50 years were recruited. After fasting for 12 hours the subjects received 10 µg of exenatide solution subcutaneously. Blood samples were taken before the administration of exenatide and up to 150 minutes thereafter. The primary outcome was the maximal level of cortisol after the administration of exenatide. Single administration of exenatide 10 µg resulted in a modest increase in ACTH and cortisol levels, as compared to untreated values, and a decrease in blood glucose levels. Remarkably, a robust suppression of both renin and aldosterone levels occurred. We showed that acute administration of exenatide in a full therapeutic dose modestly stimulates the hypothalamic-pituitary-adrenal axis but inhibits the renin-aldosterone system. Further research is warranted to confirm this finding in the placebo-controlled study.

Liraglutide Treatment May Affect Renin and Aldosterone Release.

Nowadays, GLP-1 receptor agonists are widely used as effective and safe antidiabetic medications. In addition to glucose-dependent insulin secretion, their effects reach beyond glucose control. Previously, it has been shown that acute administration of GLP-1 receptor agonists increases circulating glucocorticoid and mineralocorticoid levels in both humans and rodents. So far, no studies have reported the effects of chronic administration of GLP-1 receptor agonists on the hypothalamic-pituitary-adrenal axis in humans. The aim of the current study was to examine the effects of acute and chronic treatment with the GLP-1 receptor agonist liraglutide on adrenal function in humans. Ten healthy volunteers were recruited into a single group open-label clinical trial. Each participant was tested for baseline levels, and after acute and chronic treatment with 0.6 mg liraglutide daily. A graded glucose infusion test was performed 3 times. We found that aldosterone tended to be suppressed (albeit not statistically different) after acute administration of liraglutide, and increased after chronic dosing; the difference was statistically significant when compared between acute and chronic dosing. Changes in aldosterone levels followed the changes in renin concentrations and the aldosterone-to-renin ratio remained stable. No statistically significant differences were observed in ACTH or cortisol levels. In conclusion, we have shown that a low dose of GLP-1 receptor agonist may interfere with renin and aldosterone release. Further studies in a larger patient sample and with higher doses of GLP-1 receptor agonists are warranted to corroborate this finding. The study protocol was registered at clinical.trials.gov (NCT02089256) and EU Clinical Trial Register (2014-000238-43).