Oral hypoglycaemic agents for the treatment of gestational diabetes mellitus: systematic review of the literature

Background: gestational diabetes mellitus (GDM) is associated to a higher maternal and perinatal risk. Usually GDM is controlled with diet, exercise and insulin. Oral hypoglycaemic agents (OHA) are an emergent therapy for the treatment of GDM. Objectives: conduct a systematic review of all class I evidence available regarding the use of OHA for GDM treatment, and perform a metaanalysis of significant maternal and perinatal outcomes. Results: ten studies accomplished inclusion criteria. Three studies compared metformin to insulin, four compared glyburide to insulin and three compared metformin to glyburide. Studies showed no significant differences in glycaemic control or perinatal complications, between metformin and insulin, between glyburide and insulin, or between metformin and glyburide. Our metaanalysis comparing OHA to insulin shows significantly lower fasting blood glucose (MD 1.74; 95 percent IC 0.38-3.10) and larger 2-hr postprandial glucose in the insulin group compared to OHA groups (MD -2.97; 95 percent IC -27.24-5.36). Our metaanalysis comparing shows a significantly lower incidence of large for gestational age in the metformin vs. gliburide group (OR 0.38; 95 percent IC 0.18-0.78). Failure of treatment was significantly lower using gliburide than metformin (27.6 percent vs. 38.5 percent, p<0.0001; 95 percent IC 1.21-1.60). Conclusion: OHA are a safe and effective treatment for GDM. We recommend the use of glyburide (glibenclamide) in GDM patients that fail to obtain glycemic control with diet and exercise, since glyburide does not crosses the placental barrier, has a lower rate of treatment failure and is equally affective as metformin.