Effect of vildagliptin as add-on therapy to a low-dose metformin

AIM: To evaluate the efficacy and safety of the addition of vildagliptin to low-dose metformin and compare it to an uptitration of metformin in type 2 diabetes mellitus (T2DM) patients who have inadequate control with metformin monotherapy.METHODS: Eligible patients were randomized to receive vildagliptin 100 mg qd or metformin (500 mg qd for 2 wk and then 500 mg bid) added to open label metformin 500 mg bid for the 24 wk. The primary endpoint was baseline to endpoint hemoglobin A_1c (HbA_1c) change.RESULTS: The adjusted mean change from baseline in HbA_1c at the 24th wk was -0.51% in the vildagliptin/metformin group (mean baseline HbA_1c: 7.4%) and -0.37% in the metformin monotherapy group (mean baseline HbA_1c: 7.3%). The mean difference was -0.14% with 95% Confidence Interval (-0.24%, -0.05%). As non-inferiority (margin of 0.4%) was achieved, a test for superiority was performed. This test showed statistically significant superiority of the combination over monotherapy group (P = 0.002). Gastrointestinal (GI) adverse events were significantly more frequent in the metformin group than the combination group (21.0% vs 15.4%, P = 0.032).CONCLUSION: In patients with T2DM inadequately controlled with metformin up to 1000 mg daily, the addition of vildagliptin 100 mg daily achieved larger HbA_1c reduction with fewer GI events than with increasing the metformin dose.