Is metformin more efficient than glyburide in achieving glycemic control in patients with gestational diabetes?

From: The American College of Obstetricians and Gynecologists

Journal rating:
rating: 97%
Study Quality:
rating: 85%

Overall Reliability

Article Quality:
rating: 65%
rating: 25%


  • 149 patients with gestational diabetes who did not achieve glycemic control on diet.


  • All women were given counselling on diet and exercise and were initially treated with diet. Women who did not maintain a specified fasting blood glucose were offered participation in the study
  • Included patients were randomly assigned to metformin (number=75) or glyburide (n=74).
  • Women in the glyburide group received an initial dose of 2.5 mg twice daily, which was increased as necessary to a maximum dose of 20 mg/d (10 mg twice daily). The initial dose of metformin was 500 mg/d, taken in divided doses and increased as necessary to a maximum dose of 2 g/d. Glucose levels were reviewed weekly. 


  • 26 patients in the metformin group (34.7%) and 12 patients in the glyburide group (16.2%) did not achieve adequate glycemic control and required insulin therapy.
  • The failure rate of metformin was 2.1 times higher than the failure rate of glyburide (34.7% of patients eventually requiring insulin therapy, compared with 16% who required insulin therapy in the glyburide group).
  • There was a higher rate of nonelective cesarean deliveries and smaller birth weights in the metformin group.


  • No (with confidence)


Editors Notes

  • Note that all women were instructed on a diet designed to provide 30 kcal/kg of normal body weight and 25 kcal/kg of body weight in obese women. The diet was also designed so that 40% of calories came from carbohydrates, 20% came from protein, and 30–40% came from fats.
  • Calories were distributed 10% at breakfast, 20 –30% for lunch and dinner, and 30% for snacks. The importance of exercise in the management of blood glucose was emphasized, and 30 minutes of walking per day was recommended.