Metformin Plus Insulin vs. Insulin Alone in Patients with Type 2 Diabetes

Many patients with type 2 diabetes who are treated with metformin eventually require insulin. Although metformin often is continued in such patients, whether combining the drugs yields any benefit is unclear. In this meta-analysis of 23 randomized trials that involved more than 2100 participants (trial durations, 3–24 months), investigators compared metformin plus insulin with insulin alone.

Patients randomized to metformin plus insulin required less insulin (mean difference, –19 units/day), experienced better glycemic control (mean glycosylated hemoglobin [HbA_1c] difference, –0.6%) and weighed less (mean difference, –1.7 kg) than did patients randomized to insulin alone. Hypoglycemia was more common in the metformin-plus-insulin group. All-…