Effect of race and ethnicity on vildagliptin efficacy: A pooled analysis of phase II and III studies

Aims To determine the impact of race and ethnicity on the efficacy, body weight and hypoglycaemia incidence with vildagliptin treatment in patients with type 2 diabetes mellitus using patient-level data from the vildagliptin clinical trial programme. Methods Data from 22 randomized, placebo-controlled global and local (Japan, China) registration studies of vildagliptin (50 mg once-daily or twice-daily) of ≥12-week duration were analysed by race (Caucasian [n = 2764] and Asian [n = 2232]) and by ethnicity (Japanese, Chinese, and Indian). The placebo-subtracted differences in the change in glycated haemoglobin (HbA1c) and body weight from baseline to week 12 or week 24 were evaluated by race or ethnicity using repeated measure analysis of unstructured covariance. Hypoglycaemia incidences were summarized using descriptive statistics. Results The HbA1c reduction from baseline with vildagliptin was similar across the racial/ethnic subgroups (−0.83% ± 0.02% to −1.01% ± 0.05%). Placebo-corrected HbA1c reduction was similar between Caucasian (−0.68% ± 0.03%) and Asian (−0.80% ± 0.03%) patients ( P value for interaction = .56); analysis by race and ethnicity showed better efficacy ( P < .02) in Japanese patients. Japanese patients were drug-naive and treated with a single oral anti-diabetes drug only; they showed no response to placebo. Weight neutrality of vildagliptin was demonstrated in all groups (0.47 ± 0.11 kg to −0.29 ± 0.08 kg). Hypoglycaemic events (≥1) were infrequent in all ethnic subgroups. Conclusions The glycaemic efficacy of vildagliptin was similar in Caucasian and Asian patients. The slightly better efficacy observed in Japanese patients was driven by the absence of placebo effect and might be explained by their earlier stage of diabetes compared to other subgroups.