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Gestational diabetes (GDM) affects about 4% of pregnancies. Insulin is standard therapy for GDM that is not controllable by diet; the optimal oral agent to control blood glucose, however, is unknown. Investigators in New Mexico randomized 149 GDM patients (86% Latina) to metformin or glyburide and compared the medications' efficacy in maintaining glycemic control (defined as fasting blood glucose ≤105 mg/dL and 2-hour postprandial glucose ≤120 mg/dL).
Participants who received glyburide were more than twice as likely to achieve glycemic control than were metformin users (35% vs. 16%; odds ratio, 2.7). However, mean birth weight of infants in the metformin group was lower than that of glyburide infants (P=0.02). Incidence of preeclampsia, maternal hypoglycemia, and fetal macrosomia was similar in both groups.
Moore LE et al. Metformin compared with glyburide in gestational diabetes: A randomized controlled trial. Obstet Gynecol 2010 Jan; 115:55.
Comment
These results show that glyburide provides better control of blood glucose than does metformin; however, the study's small size limits our ability to compare secondary outcomes (e.g., neonatal outcomes, cesarean delivery rate). In addition, results might not be generalizable to all patients, given that the vast majority of participants in this study were Latina. Although the possible effects of ethnicity on the results are unknown, the failure rate of metformin is consistent with that observed in the Metformin in Gestational Diabetes Trial (JW Womens Health May 7 2008). The authors note that the lower birth weights in the metformin group might reflect the potential benefits of metformin as an insulin sensitizer that can cross the placenta. Because patients are more likely to prefer and adhere to oral treatment of GDM, an oral medication for effective control of blood glucose during pregnancy would be highly desirable. If larger studies confirm these results, glyburide could be the oral agent of choice for treatment of women with GDM.