Treatment of GDM with Oral Hypoglycemic Drugs
ABSTRACT & COMMENTARY
Synopsis: In women with gestational diabetes, glyburide is a clinically effective alternative to insulin therapy.
Source: Langer O, et al. N Engl J Med 2000;343:1134-1138.
To determine if glyburide, a second-generation sulfonylurea drug could be safely and effectively used to treat gestational diabetes mellitus (GDM), these researchers conducted a prospective, randomized trial, with 201 women receiving glyburide and 203 insulin. All patients had failed diet therapy as evidenced by fasting glucose concentrations greater than 95 mg/dL or postprandial glucose levels greater than 120 mg/dL. Treatment was initiated at approximately 25 weeks gestation, and the average dose of glyburide was 9 mg/d with a maximum dose of 20 mg/d. Women receiving insulin took three injections with an average dose of 85 u/d.
Based on capillary glucose measurements performed seven times each day, all patients achieved excellent glucose control with an average glucose level of 105 mg/dL. No differences were noted in glycosylated hemoglobin levels. Hypoglycemia, defined as a glucose less than 40 mg/dL, occurred in only four women in the glyburide group but was noted in 41 women receiving insulin, a significant difference. Only eight women in the glyburide group (4%) failed to maintain good glucose control on the maximal dose of this drug, and they were switched to insulin. No differences were noted in perinatal outcome in the glyburide and insulin treatment groups, including large for gestational age infants, 12% vs. 13%, and birth weights greater than 4000 g, 7% vs. 4%, respectively. Cord blood insulin concentrations were similar in both groups, and glyburide was not detected in the cord blood of any infant.
Langer and colleagues concluded that, in women with gestational diabetes, glyburide is a clinically effective alternative to insulin therapy.
Comment by Steven G. Gabbe, MD
For decades, insulin has been the treatment of choice for women with GDM who fail diet therapy. Oral hypoglycemic agents were said to be contraindicated and understandably so. The first-generation sulfonylurea drugs crossed the placenta and stimulated the fetal pancreatic beta-cells producing hyperinsulinemia and excessive fetal growth. Furthermore, profound neonatal hypoglycemia was observed after delivery. In earlier studies, Langer et al demonstrated that glyburide was different. Using a perfused placental model, they found that glyburide did not cross the placenta and decided to try this therapy in women with GDM.1 Excellent maternal glucose control was achieved, and maternal hypoglycemia was reduced when compared to women using insulin. Perinatal outcome was no different. We have begun to give glyburide to selected patients in our clinic, particularly in women who have difficulty counting and measuring an insulin dose. A word of caution is warranted. Other oral hypoglycemic agents should not be used until carefully performed studies comparable to this one have been conducted.
Reference
1. Elliott BD, et al. Am J Obstet Gynecol 1991;165:807-812.
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