Randomized trial of metformin vs insulin in the management of gestational diabetes.

Objective: To evaluate glycemic control in women receiving metformin or insulin for gestational diabetes, and to identify factors predicting the need for supplemental insulin in women initially treated with metformin.

Study Design: Women with gestational diabetes who failed to achieve glycemic control with diet and exercise were randomized to receive metformin (n = 47) or insulin (n = 47). Criteria for inclusion were singleton pregnancy, diet, and exercise for a minimum period of 1 week without satisfactory glycemic control, absence of risk factors for lactic acidosis, and absence of anatomic and/or chromosome anomalies of the conceptus.