Pregnancy outcomes after metformin treatment for gestational diabetes: a case-control study

There is increasing evidence that metformin is safe and effective in the treatment of gestational diabetes (GDM), although it has not yet been widely accepted for routine practice. We compared pregnancy outcomes in women with gestational GDM treated with metformin or dietary measures alone.

Women with GDM (324) not adequately controlled by diet received metformin according to protocol based on their home glucose results. Pregnancy outcomes in these women were compared with 175 GDM women treated with diet alone and matched for age and ethnicity.

The percentage of macrosomic babies (birth weight [BW] centile >90th centile) and small for gestational age (SGA) (BW <10th centile) in the metformin group was significantly reduced compared with the diet group (12.7% versus 20%; P < 0.05 [macrosomia]; 7.7% versus 14.3% [SGA] P < 0.05).

Metformin treatment had a favourable impact on the rates of macrosomia and SGA despite more severe glucose intolerance at baseline.