Type 2 diabetes is becoming more frequent in pregnant women. The actions of metformin, including improved sensitivity to insulin, make it a logical treatment option. Metformin also suppresses endothelial activation, which is increased in pregnancy, and it reduces gluconeogenesis in the liver while increasing peripheral glucose uptake. The investigators examined pregnancy outcomes in 214 pregnancies in which type 2 diabetes had been diagnosed. Metformin was taken during 93 pregnancies and was continued to the time of delivery in 32 of them.
Metformin-treated women had greater body mass indices than nonusers. They also had chronic hypertension more frequently (19% vs 7%, P < .05) and higher levels of glycated hemoglobin in the first trimester. The metformin-treated and control groups did not differ significantly with respect to rates of preeclampsia, perinatal loss, prematurity, or neonatal morbidity. Differences in rates of admission to the neonatal unit, respiratory distress, and intravenous dextrose administration did not differ significantly between women given metformin and the others. Congenital abnormalities were not more frequent in the offspring of women taking metformin at any time during pregnancy.
These outcomes are encouraging for pregnant women having type 2 diabetes, but it is not yet clear whether metformin treatment should be recommended for use by these women. Randomized trials will be needed to make this determination.