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Reference: JAMA Pediatr 2015 May 1;169(5):452 (level 2 [mid-level] evidence)
Gestational diabetes mellitus affects approximately 7% of all pregnancies and is associated with increased risk of maternal and neonatal complications (Diabetes Care 2014 Jan;37 Suppl 1:S81, Diabetes Care 2007 Jul;30 Suppl 2:S251). Identification and proper treatment of gestational diabetes, however, may decrease these risks (BMJ 2010 Apr 1;340:c1395, N Engl J Med 2009 Oct 1;361(14):1339). The American Diabetes Association recommends initial management of gestational diabetes with diet and exercise, with the addition of insulin or oral hypoglycemic agents if needed (Diabetes Care 2015 Jan;38 Suppl 1:S1 PDF). Currently, the evidence comparing insulin to oral hypoglycemic agents including glyburide is limited. A recent retrospective cohort study assessed maternal and neonatal outcomes in 9,137 privately insured women with gestational diabetes prescribed glyburide or insulin within 150 days of delivery. All included women had singleton pregnancies.
The mean duration of treatment was 50.4 days for the 4,982 women (54.3%) prescribed glyburide and 54.1 days for the 4,191 women (45.7%) prescribed insulin. In an analysis adjusted for age and other covariates, use of glyburide was associated with increased risk of neonatal complications compared to insulin, including neonatal intensive care unit admission (adjusted relative risk [RR] 1.41, 95% CI 1.23-1.62, NNH 25-60), respiratory distress (adjusted RR 1.63, 95% CI 1.23-2.15, NNH 61-233), and large for gestational age (adjusted RR 1.43, 95% CI 1.16-1.76, NNH 46-164). Glyburide was also nonsignificantly associated with an increased risk of hypoglycemia and birth injury, but there were no significant differences in the risk of obstetric trauma, cesarean delivery, jaundice, or prematurity.
Although limited by its retrospective cohort design, this study allows for the examination of a much larger group of women than reported in previous observational studies or randomized trials. The largest randomized trial comparing glyburide vs. insulin included 404 women and found no significant differences in neonatal outcomes (N Engl J Med 2000 Oct 19;343(16):1134), but the trial was likely underpowered to detect differences in these outcomes. The results of the current study are consistent with the direction of outcomes in the prior trial, but the 20-fold larger patient population increased the ability of this study to detect differences in neonatal outcomes affecting a small percentage of patients. The study also reflects real world conditions rather than the tightly controlled protocols found in many randomized trials. Overall, the results of this study suggest that glyburide may be associated with a greater risk of complications than insulin in women with gestational diabetes requiring medication.
For more information, see the Gestational diabetes mellitus (GDM) topic in DynaMed.