Additive postprandial glucose-lowering effects of mitiglinide and sitagliptin in patients with type 2 diabetes mellitus

Introduction: The aim of this research was to compare the pharmacodynamics of the combination of mitiglinide and sitagliptin to that of each agent alone in Korean patients with type 2 diabetes mellitus (T2DM). Methods: Patients with T2DM received mitiglinide alone, sitagliptin alone, or both drugs together in randomized sequence. A meal tolerance test (MTT) was conducted for each group, and plasma concentrations of glucose, insulin, C-peptide, glucagon, and intact glucagon-like peptide-1, and dipeptidyl peptidase-4 activity were measured from 2 h before breakfast through 4 h after breakfast on day 0 (pretreatment) and day 1 (posttreatment) of each treatment period. Integrated values of these pharmacodynamic variables were analyzed for changes from pretreatment to posttreatment and for differences between the three treatment groups. Results: Twenty-six patients with glycated hemoglobin A_1c level of 7.4% ± 0.6%, fasting plasma glucose concentration of 141 ± 22 mg/dL, postprandial plasma glucose (PPG) concentration of 264 ± 48 mg/dL 1 h after the MTT, and diabetes duration of 3.0 ± 3.1 years (mean ± SD) were included in the study. Compared with mitiglinide or sitagliptin alone, the combination treatment lowered PPG additively (P < 0.001 vs. mitiglinide or sitagliptin alone) and the insulin secretory response (P = 0.03 vs. mitiglinide or sitagliptin alone). The integrated insulin concentrations changed significantly from before to after treatment (P < 0.01), but the change did not differ between the combination and mitiglinide groups. The insulinogenic index increased significantly after the combination treatment (P < 0.001 vs. mitiglinide or sitagliptin alone). The combination of mitiglinide and sitagliptin was generally well tolerated, with no hypoglycemic events. Conclusions: The combination of mitiglinide and sitagliptin did not trigger hypoglycemia and controlled postprandial glucose excursion more effectively compared with either drug alone.