TREATMENT OF GESTATIONAL DIABETES MELLITUS: INSULIN OR METFORMIN?

BACKGROUND Metformin has established as an ideal first-line treatment for type 2 diabetes and hypothetically a particularly attractive drug for use in pregnancy. Metformin is known to cross the placenta and its use in pregnancy has been limited by concerns regarding potential adverse effects on both the mother and the foetus. Randomised trials to assess the efficacy and safety of its use for Gestational Diabetes Mellitus (GDM) are lacking. METHODS Seventy six women with singleton pregnancy and diagnosed with GDM as per International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria were enrolled in study at 24 to 33 weeks of gestation. Subjects were randomly allocated to the intervention group (n=38) and active control group (n=38). Each subject in both groups received counseling on diet modification and physical activity, but failed to achieve glycaemic targets. Intervention group received metformin (with supplemental insulin if required). Active control group received human insulin (Regular, Neutral Protamine Hagedorn (NPH), or both). Primary outcome was neonatal birth weight. Secondary outcomes included maternal and neonatal complications with treatment satisfaction for allotted modality. RESULTS A total of 32 on metformin (Intervention group) and 33 on insulin (Active control group) subjects completed study. Of the 32 women assigned to metformin, 96.87% continued to receive metformin until delivery and 25% of the metformin group received supplemental insulin. There was no significant difference in mean birth weight between groups. There were no significant differences in neonatal and maternal complications between groups. However, treatment satisfaction (70.97%) was significantly better in metformin group whereas better control of postprandial plasma glucose was achieved in insulin group. CONCLUSIONS Metformin is an effective, safe, cheap, and convenient alternative to insulin in the treatment of GDM patients. However, to determine the predictors of the need for supplemental insulin in women treated with metformin, will require further study.