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

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.

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.

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).

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.