Objective: To evaluate whether the addition of glyburide to diet therapy modifies pregnancy outcomes in women with mild gestational diabetes.
Methods: Women with at least two abnormal values on a 3-hour, 100-g oral glucose tolerance test according to National Diabetes Data Group criteria and fasting values less than 105 mg/dL between 24 and 30 weeks of gestation were randomized to blinded glyburide or placebo study drug. All women were placed on a 35-kcal/kg diet and recorded four times daily capillary glucose measurements. The study drug was titrated based on weekly maternal capillary glucose values with targets of less than 95 mg/dL (5.3 mmol/L) and 120 mg/dL (6.7 mmol/L) for fasting and 2-hour postprandial glucose measurements, respectively. The primary study outcome was a 200-g birth weight decrement in neonates of women treated with glyburide. The sample size estimate for this outcome was 334 total randomized women with a one-to-one allocation.
Results: A total of 395 women were enrolled at a single center between September 2008 and October 2012. Women treated with glyburide had a significantly greater decline in fasting glucose values over the course of therapy. However, there was no difference in the primary study outcome. Specifically, the mean birth weight was 33 g lower in the group treated with glyburide (P=.52). Although not powered to examine all outcomes associated with gestational diabetes, treatment with glyburide did not affect need for operative delivery, shoulder dystocia, clavicular fracture, Erb's palsy, or neonatal hypoglycemia. Four women in each group required insulin.
Conclusion: The addition of glyburide to diet therapy significantly improved maternal glycemic control over time when compared with placebo. However, adding glyburide to diet did not decrease birth weight or improve maternal or neonatal outcomes in women with mild gestational diabetes.
Clinical trial registration: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00744965.
Level of evidence: I.