Feig DS, Donovan LE, Zinman B, et al. - Researchers examined how the addition of metformin to a standard regimen of insulin affects neonatal morbidity and mortality in pregnant women with type 2 diabetes. They conducted a prospective, multicenter, international, randomized, parallel, double-masked, placebo-controlled trial, randomizing 502 women with type 2 diabetes during pregnancy to receive either metformin 1,000 mg twice daily or placebo, added to insulin. The metformin group exhibited several maternal glycemic and neonatal adiposity benefits. Along with lower maternal weight gain and insulin dosage and improved glycemic control, the lower adiposity and infant size measures led to fewer large infants but a greater proportion of small-for-gestational-age infants. Ascertaining the implications of these effects on infants will be important to adequately guide patients who are contemplating the use of metformin during pregnancy.