Insulin and glyburide therapy: dosage, severity level of gestational diabetes, and pregnancy outcome

We sought to investigate the association between glyburide dose, degree of severity in gestational diabetes mellitus (GDM), level of glycemic control, and pregnancy outcome in insulin- and glyburide-treated patients.

In a secondary analysis of our previous randomized study, 404 women were analyzed. The association among glyburide dose, severity of GDM, and selected maternal and neonatal factors was evaluated. Severity levels of GDM were stratified by fasting plasma glucose (FPG) from the oral glucose tolerance test (OGTT). Infants with birth weight at or above the 90th percentile were considered large-for-gestational age (LGA). Macrosomia was defined as birth weight > or =4000 g. Well-controlled was defined as mean blood glucose < or =95 mg/dL. The association between glyburide- and insulin-treated patients by severity of GDM and neonatal outcome was evaluated.

The dose received for the glyburide-treated patients was 2.5 mg-32%; 5 mg-23%; 10 mg-17%; 15 mg-8%; and 20 mg-20%. Patients were grouped into low (< or =10 mg) and high (>10 mg) daily dose of glyburide. A comparison between severity of the disease (fasting plasma glucose categories) and highest dose of glyburide revealed a significant difference between the low-95 FPG and the other severity categories (P = .02). Of patients in the well-controlled glycemic group, only 6% required the high dose of glyburide (>10 mg). In patients with poor glycemic control (mean blood glucose >95 mg/dL), 38% received the high dose of glyburide (P = .0001). Comparison between the high glyburide (>10 mg) and the low glyburide dosages (< or =10 mg) revealed that the rate of macrosomia was 16% vs 5% and LGA 22% vs 8%, (P = .01), respectively. No significant difference was found in composite outcome, metabolic complications, and Ponderal Index between the 2 dose groups. Stratification by disease severity revealed a significantly lower rate of LGA for both the glyburide- and insulin-treated subjects. No significant difference was found between metabolic, respiratory, and neonatal intensive care unit (NICU) for patients within each fasting plasma glucose severity category.

Glyburide and insulin are equally efficient for treatment of GDM in all levels of disease severity. Achieving the established level of glycemic control, not the mode of pharmacologic therapy, is the key to improving the outcome in GDM.