Background and objective: Vildagliptin and sitagliptin are oral dipeptidyl peptidase 4 inhibitors approved in Japan for the treatment of type 2 diabetes mellitus when adequate glycaemic control is not achieved with diet, exercise or sulphonylureas. The aim of this study was to compare 12-week glycaemic control with vildagliptin 50 mg twice daily versus sitagliptin 50 or 100 mg once daily in Japanese patients with type 2 diabetes.
Methods: Randomized trials of vildagliptin or sitagliptin in Japanese patients were identified from the literature. Individual patient data were obtained for vildagliptin trials. In the absence of a head-to-head randomized trial, a matching-adjusted indirect comparison was conducted by weighting individual patients from vildagliptin trials to match average baseline characteristics published for sitagliptin trials, including age, sex, body mass index, glycosylated haemoglobin (HbA(1c)), fasting plasma glucose (FPG) and diabetes duration. After matching, HbA(1c) change from baseline to week 12, the primary endpoint in each trial, was compared between balanced populations treated with vildagliptin and sitagliptin. Separate comparisons were conducted for vildagliptin 50 mg twice daily versus sitagliptin 50 mg and 100 mg once daily.
Results: Two trials of vildagliptin and three trials of sitagliptin were identified for Japanese patients. Across all included trials, a total of 264 patients were treated with vildagliptin 50 mg twice daily, 235 were treated with sitagliptin 50 mg once daily and 145 were treated with sitagliptin 100 mg once daily. Mean baseline HbA(1c) ranged from 7.4% to 7.8% per trial. Before matching, significant (p < 0.05) cross-trial differences included lower mean HbA(1c) (by 0.2-0.3%) and higher FPG (by 5-13 mg/dL) in vildagliptin trials. After matching, all baseline characteristics were balanced between treatment groups. Combining matched trials, vildagliptin 50 mg twice daily was associated with significantly greater absolute HbA(1c) reduction by 0.28% compared with sitagliptin 50 mg once daily (95% CI 0.15, 0.41; p < 0.001) and by 0.35% compared with sitagliptin 100 mg once daily (95% CI 0.07, 0.62; p = 0.013).
Conclusion: After adjusting for baseline differences among trials of vildagliptin and sitagliptin in Japanese patients with type 2 diabetes, vildagliptin 50 mg twice daily was associated with significantly greater HbA(1c) reduction than sitagliptin 50 mg or 100 mg once daily.