Aims/hypothesis Insulin secretion in pancreatic islets is dependent upon mitochondrial function and production of ATP. The transcriptional coactivator peroxisome proliferator activated receptor gamma coactivator-1 alpha (protein PGC-1α; gene PPARGC1A) is a master regulator of mitochondrial genes and its expression is decreased and related to impaired oxidative phosphorylation in muscle from patients with type 2 diabetes. Whether it plays a similar role in human pancreatic islets is not known. We therefore investigated if PPARGC1A expression is altered in islets from patients with type 2 diabetes and whether this expression is influenced by genetic (PPARGC1A Gly482Ser polymorphism) and epigenetic (DNA methylation) factors. We also tested if experimental downregulation of PPARGC1A expression in human islets influenced insulin secretion. Methods The PPARGC1A Gly482Ser polymorphism was genotyped in human pancreatic islets from 48 non-diabetic and 12 type 2 diabetic multi-organ donors and related to PPARGC1A mRNA expression. DNA methylation of the PPARGC1A promoter was analysed in pancreatic islets from ten type 2 diabetic and nine control donors. Isolated human islets were transfected with PPARGC1A silencing RNA (siRNA).Results PPARGC1A mRNA expression was reduced by 90% (p<0.005) and correlated with the reduction in insulin secretion in islets from patients with type 2 diabetes. After downregulation of PPARGC1A expression in human islets by siRNA, insulin secretion was reduced by 41% (p≤0. 01). We were able to ascribe reduced PPARGC1A expression in islets to both genetic and epigenetic factors, i.e. a common PPARGC1A Gly482Ser polymorphism was associated with reduced PPARGC1A mRNA expression (p<0.00005) and reduced insulin secretion (p<0.05). In support of an epigenetic influence, the PPARGC1A gene promoter showed a twofold increase in DNA methylation in diabetic islets compared with non-diabetic islets (p<0.04). Conclusions/interpretation We have shown for the first time that PPARGC1A might be important in human islet insulin secretion and that expression of PPARGC1A in human islets can be regulated by both genetic and epigenetic factors.

Several common genetic variations have been associated with type 2 diabetes, but the exact disease mechanisms are still poorly elucidated. Using congenic strains from the diabetic Goto-Kakizaki rat, we identified a 1.4-megabase genomic locus that was linked to impaired insulin granule docking at the plasma membrane and reduced beta cell exocytosis. In this locus, Adra2a, encoding the alpha2A-adrenergic receptor [alpha(2A)AR], was significantly overexpressed. Alpha(2A)AR mediates adrenergic suppression of insulin secretion. Pharmacological receptor antagonism, silencing of receptor expression, or blockade of downstream effectors rescued insulin secretion in congenic islets. Furthermore, we identified a single-nucleotide polymorphism in the human ADRA2A gene for which risk allele carriers exhibited overexpression of alpha(2A)AR, reduced insulin secretion, and increased type 2 diabetes risk. Human pancreatic islets from risk allele carriers exhibited reduced granule docking and secreted less insulin in response to glucose; both effects were counteracted by pharmacological alpha(2A)AR antagonists.

Background Oral semaglutide is a novel tablet containing the human glucagon-like peptide-1 (GLP-1) analogue semaglutide, co-formulated with the absorption enhancer sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC). The safety and pharmacokinetics of oral semaglutide were investigated in two randomised, double-blind, placebo-controlled trials. Methods In a single-dose, first-inhuman trial, 135 healthy males received oral semaglutide (2-20 mg semaglutide coformulated with 150-600 mg SNAC) or placebo with SNAC. In a 10-week, once-daily, multiple-dose trial, 84 healthy males received 20 or 40 mg oral semaglutide (with 300 mg SNAC), placebo, or placebo with SNAC, and 23 males with type 2 diabetes (T2D) received 40 mg oral semaglutide (with 300 mg SNAC), placebo, or placebo with SNAC. Results Oral semaglutide was safe and well-tolerated in both trials. The majority of adverse events (AEs) were mild, with the most common AEs being gastrointestinal disorders. In the single-dose trial, semaglutide exposure was highest when coformulated with 300 mg SNAC. In the multiple-dose trial, semaglutide exposure was approximately twofold higher with 40 versus 20 mg oral semaglutide in healthy males, in accordance with dose proportionality, and was similar between healthy males and males with T2D. The half-life of semaglutide was approximately 1 week in all groups. Conclusion The safety profile of oral semaglutide was as expected for the GLP-1 receptor agonist drug class. Oral semaglutide co-formulated with 300 mg SNAC was chosen for further clinical development. The pharmacokinetic results supported that oral semaglutide is suitable for once-daily dosing. ClinicalTrials.gov identifiers NCT01037582, NCT01686945.

BackgroundSemaglutide, a glucagon-like peptide-1 (GLP-1) analogue, has been co-formulated with the absorption enhancer sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC) as a tablet for oral administration. This trial (NCT02014259) investigated the pharmacokinetics, safety and tolerability of oral semaglutide in subjects with and without renal impairment.MethodsSubjects were categorised as having normal renal function (n = 24), mild (n = 12), moderate (n = 12) or severe (n = 12) renal impairment, or end-stage renal disease (ESRD) requiring haemodialysis (n = 11) and received once-daily oral semaglutide (5 mg for 5 days followed by 10 mg for 5 days) in the fasting state, followed by 30 min fasting after dosing. Semaglutide plasma concentrations were measured during dosing and for up to 21 days after the last dose.ResultsSemaglutide exposure (area under the plasma concentration–time curve from time zero to 24 h after the tenth dose and maximum concentration after the tenth dose) did not vary in a consistent pattern across the renal function groups. Similarly, there was no apparent effect of renal impairment on the semaglutide half-life (geometric mean range 152–165 h). Except for one subject in the ESRD group, semaglutide was not detected in urine. Haemodialysis did not affect the pharmacokinetics of semaglutide. Adverse events were in line with those observed for other GLP-1 receptor agonists and no safety concerns were identified.ConclusionThere was no apparent effect of renal impairment or haemodialysis on the pharmacokinetics of oral semaglutide. Based on this trial, renal impairment should not affect dose recommendations for oral semaglutide.

Insulin degludec (IDeg) is a basal insulin with an ultra-long pharmacokinetic profile in adults that at steady-state produces remarkably flat and stable insulin levels; however, no studies have yet reported on the pharmacokinetic properties of IDeg in subjects younger than 18 years of age. This was a single-centre, randomised, single-dose, double-blind, two-period crossover trial conducted in children (6-11 years), adolescents (12-17 years), and adults (18-65 years) with type 1 diabetes. Subjects received a single subcutaneous dose of 0.4 U/kg IDeg or insulin glargine (IGlar), respectively, on two separate dosing visits, with pharmacokinetic blood sampling up to 72-h postdose. A total of 37 subjects (12 children, 13 adolescents, and 12 adults) completed the trial. Total exposure of IDeg after a single dose (AUCIDeg ,0-∞, SD ) was higher in children compared to adults [estimated ratio children/adults 1.48 (95% confidence interval, CI: 0.98; 2.24)] and in adolescents compared to adults [estimated ratio adolescents/adults 1.33 (95% CI: 1.08; 1.64)]; however, the difference was only statistically significant for the latter comparison. No statistically significant difference in maximum concentration of IDeg (Cmax, IDeg , SD ) was observed. Estimated ratios for Cmax, IDeg , SD were (children/adults) 1.20 (95% CI: 0.90; 1.60) and (adolescents/adults) 1.23 (95% CI: 1.00; 1.51). Simulated mean steady state pharmacokinetic profiles supported a flat and stable IDeg exposure across a 24-h dosing interval. IDeg was detectable in serum for at least 72 h (end of blood sampling period) in all subjects following single dose. In conclusion, the ultra-long pharmacokinetic properties of IDeg observed in adults are preserved in children and adolescents with type 1 diabetes.