Metformin in Gestational Diabetes Mellitus

As currently diagnosed, gestational diabetes mellitus (GDM) affects 5–9% of all pregnancies in the United States and is growing in prevalence. 1 It is defined as carbohydrate intolerance of variable severity that is first recognized during pregnancy. Although GDM has been recognized for decades, the potential significance of the condition, as well as criteria for screening and diagnosis , remain debatable. 1 Historically, GDM has been treated with lifestyle modifications and insulin, and oral antihyperglycemic agents have been used infrequently because of concerns regarding neonatal hypo-glycemia and teratogenicity. Most recent studies suggest that oral hypoglycemic agents, specifically metformin, are safe to use during pregnancy (Table 1). 2–13 Risk for developing GDM has been noted in women who are overweight before pregnancy, have had GDM in a previous pregnancy, or have a family history of diabetes. Poorer outcomes have been seen in both pregnant women and their developing fetuses, including induction of labor and caesarean delivery in women and death, shoulder dys-tocia, bone fracture, and nerve palsy in fetuses. 1 Moreover, recent studies show that diagnosis and management of this disorder will have beneficial effects on both maternal and neonatal outcomes. According to the American College of Obstetrics and Gynecology, comprehensive screening techniques have been implemented by > 90% of practices in the United States. 16 Reasons for the implementation of screening programs were developed from the evidence obtained in the Hyperglycemia and Adverse Pregnancy Outcomes study. 17 This large, prospective, observational study found possible adverse effects associated with even mild maternal hyperglycemia. It included a cohort of women with glucose levels at the upper end of the normal range, as well as women with mild GDM. The investigators found a linear correlation between higher levels of maternal glucose and adverse outcomes, including increased birth weight, first-time caesarean delivery, fetal C-peptide levels, and neonatal hypoglycemia. 17 Based on these findings, it has been suggested that screening for undiagnosed type 2 diabetes should occur at the first prenatal visit in women with risk factors for GDM. 1 Women not previously known to have diabetes and who have no risk factors should be screened for GDM at 24–28 weeks of gestation. 1 Because of the increasing prevalence of obesity and diabetes, detection of overt diabetes in early pregnancy has become a vital aspect of care standards. On diagnosis of GDM, treatment consists of glucose monitoring, dietary modification, and lifestyle interventions. 1 If necessary, …