Treatment of mild GDM has some benefits

Clinical question Does the treatment of mild gestational diabetes mellitus (GDM) improve pregnancy outcomes?

Bottom line The treatment of mild GDM did not reduce the incidence of the primary outcome: a composite of stillbirth, perinatal death, and neonatal complications. It did reduce incidences of fetal overgrowth, shoulder dystocia, cesarean delivery, and maternal hypertensive disorders. We still need randomized trials of screening versus no screening for GDM. (Level of evidence = 1b)

Synopsis These authors randomized women with mild GDM (N = 958) to receive treatment or usual prenatal care (control group). Mild GDM was defi ned as two abnormal glucose levels on 3-hour glucose tolerance testing and with a fasting glucose level of less than 95 mg/dL. The diagnosis of GDM was made between 24 and 31 weeks' gestational age. The treatment consisted of daily self-monitoring of fasting and 2-hour postprandial glucose levels with initiation of insulin therapy if the majority of glucose measurements were abnormal (fasting = 95 mg/dL or more; 2-hour postprandial = 120 mg/dL or more). In the control group, blood sugars were measured at the discretion of the patient's caregiver, who initiated treatment at a fasting blood sugar level of 95 mg/dL or higher or a random blood sugar level of 160 mg/dL or higher. There was no difference in the primary composite outcome of perinatal death and neonatal complications. There were no perinatal deaths in either group, but there were differences in adverse outcomes on several secondary measures. There was a reduction in large-for- gestational-age newborns in the treated group (7% vs 15%; number needed to treat [NNT] = 14; 95% CI, 9-29). Similarly, the incidence of birthweight more than 4,000 g was reduced in the treated group (6% vs 14%; NNT= 12; 12-22). The use of maneuvers to reduce shoulder dystocia was less frequent in the treated group (1.5% vs 4%; NNT= 40; 21-262). Hypertensive disorders were also less frequent in the treated group (9% vs 14%; NNT= 20; 11-103). Importantly, there were fewer cesarean deliveries in the treated group (27% vs 34%; NNT= 14; 8-95). The study was too small to detect clinically meaningful differences in rare outcomes.

Landon MB, Spong CY, Thom E, et al; Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. A multicenter, randomized trial of treatment for mild gestational diabetes. N Engl J Med. 2009;361(14):1339-1348.