Maternal and Neonatal Outcomes of Metformin Treatment in Pregnant Women with Type 2 Diabetes

To investigate the effects of metformin treatment on pregnancy outcomes, investigators in Canada and Australia conducted a placebo-controlled trial in 502 pregnant women with type 2 diabetes diagnosed before 20 weeks' gestation who were taking insulin daily (gestational range, 6 weeks to <23 weeks; mean age, 35; mean prepregnancy body-mass index, 34 kg/m²; mean baseline HbA_1c concentration, 6.4%). Participants were randomized to metformin (1000 mg twice daily) or placebo; all were instructed to measure capillary blood glucose daily at the following times: prior to the first meal, before the last meal, and 2 hours after each meal. Insulin was adjusted to achieve targets for fasting glucose (<95 mg/dL) and 2-hour postprandial glucose (120 mg/…