Efficacy and Safety of a Single-Pill Combination of Vildagliptin and Metformin in Japanese Patients with Type 2 Diabetes Mellitus: A Randomized, Double-Blind, Placebo-Controlled Trial

Introduction: The use of dipeptidyl peptidase-4 inhibitors in combination with metformin is increasing in Japanese patients with type 2 diabetes mellitus (T2DM), but no single-pill combination (SPC) is currently available in Japan. The objective of this study was to assess the efficacy and safety of vildagliptin/metformin SPC in Japanese patients with T2DM inadequately controlled with vildagliptin monotherapy. Methods: This was a 14-week, randomized, double-blind, parallel-group, placebo-controlled trial. 171 patients with T2DM inadequately controlled [HbA1c (glycosylated hemoglobin) 7.0-10.0%] with vildagliptin 50 mg twice daily (bid) were randomized (2: 1) to receive either a vildagliptin/metformin SPC (n = 115) or matching vildagliptin/placebo SPC (n = 56). Results: Baseline demographics and background characteristics were generally comparable between the treatment groups. The change in HbA1c [mean +/- standard error (SE)] was -0.8 +/- 0.1% in the vildagliptin/metformin SPC (baseline HbA1c, 7.9 +/- 0.1%) group and 0.1 +/- 0.1% in the vildagliptin/placebo SPC (baseline HbA1c, 8.0 +/- 0.1%) group, with a between-treatment difference of -1.0 +/- 0.1% (P<0.001) in favor of the vildagliptin/metformin SPC group. The proportion of patients achieving target HbA1c <7.0% was significantly higher with vildagliptin/metformin SPC compared with vildagliptin/placebo SPC (45.8% vs. 13.5%, P<0.001). The overall incidences of adverse events (AEs) were 43.5% in the vildagliptin/metformin SPC and 67.9% in the vildagliptin/placebo SPC group. The incidences of serious AEs were low in both the treatment groups (0.9% vs. 3.6%, respectively). Body weight remained constant throughout the study in both the treatment groups. There were no deaths or hypoglycemic events during the study. Conclusions: Switching Japanese patients with T2DM requiring treatment intensification, from vildagliptin monotherapy to a vildagliptin/metformin SPC (50/250 or 50/500 mg) was efficacious and safe, eliciting significant reduction in HbA1c without increased risk of hypoglycemia and weight gain.