G protein-coupled receptor 119 agonist DS-8500a effects on pancreatic β-cells in Japanese type 2 diabetes mellitus patients

Aims/Introduction Pancreatic beta-cell dysfunction contributes to type 2 diabetes mellitus progression. Drugs that improve insulin secretion might be a valuable treatment approach. The present study aimed to evaluate the effect of the G protein-coupled receptor 119 agonist DS-8500a on insulin secretory capacity in Japanese type 2 diabetes mellitus patients. Materials and Methods This single-center, 4-week, randomized, double-blind, cross-over study enrolled 21 Japanese drug-naive type 2 diabetes mellitus patients aged >= 20 years with glycated hemoglobin >= 7.0 and <9.0% (NCT02669732, JapicCTI 163126). Patients received 75 mg of DS-8500a or a placebo orally daily for 4 weeks in a random order. A combined euglycemic-hyperinsulinemic and hyperglycemic clamp test was carried out to assess insulin secretion and insulin sensitivity before and after each 4-week treatment period. Primary end-points were first-phase insulin secretion (insulin area under the curve [AUC](180-190 min) and C-peptide AUC(180-190 min) during the clamp test) and second-phase insulin secretion (insulin AUC(190-300 min) and C-peptide AUC(190-300 min)). Insulin sensitivity (M and M/I values), disposition index and changes in lipid profile were also assessed. Results DS-8500a significantly increased first- and second-phase insulin AUC (P = 0.0011, P = 0.0112) and C-peptide AUC (P = 0.0012, P < 0.0001) compared with the placebo. At day 28, M and M/I values were comparable with those of the placebo, whereas the disposition index for insulin and C-peptide was significantly increased (P = 0.0108, P = 0.0002). Total cholesterol, low-density lipoprotein cholesterol and triglyceride concentrations were significantly reduced, and high-density lipoprotein cholesterol concentrations were significantly increased compared with the placebo. No significant treatment-emergent adverse events occurred. Conclusion DS-8500a enhanced insulin secretory capacity, but not insulin sensitivity.