ObjectiveThe aim of the present study was to assess the efficacy and safety of vildagliptin as add-on to sulfonylurea therapy in Chinese patients with type 2 diabetes mellitus (T2DM) inadequately controlled on sulfonylurea monotherapy. MethodsThe 24-week randomized double-blind placebo-controlled study compared vildagliptin 50mg, q.d., with placebo as add-on to glimepiride in T2DM patients who were inadequately controlled (HbA1c 7.5%-11.0% [58-97mmol/mol]) on a stable dose of sulfonylurea for 12 weeks before study entry. ResultsIn all, 279 patients were randomized to receive either vildagliptin (n=143) or placebo (n=136). At baseline, overall mean age was 58.5 years, body weight 68.1kg, duration of diabetes 6.9 years and daily glimepiride dose 3.3mg. After 24 weeks, the adjusted mean change (AM) in HbA1c was -0.7% (-8mmol/mol; baseline 8.6%, 70mmol/mol) in the vildagliptin group and -0.2% (-2mmol/mol; baseline 8.7%, 72mmol/mol) in the placebo group, with a treatment difference of -0.5% (-5mmol/mol; P<0.001). The between-group difference in AM in fasting plasma glucose was -0.4mmol/L (P=0.160). There was a slight, but not significant, decrease in body weight in both groups. No hypoglycemic events were reported in either group, including those patients reaching HbA1c <7.0%. Patients in the vildagliptin and placebo groups reported low and comparable incidences of adverse events (14.0% vs 17.8%) and serious adverse events (0.7% in each group). ConclusionVildagliptin 50mg, q.d., added to sulfonylurea monotherapy is effective in Chinese patients with T2DM, without increasing the risk of hypoglycemia and weight gain.