Women with gestational diabetes are more likely to control their blood glucose levels when receiving treatment with metformin rather than insulin…
Patients included in the randomized controlled study by Pavao et al were women with gestational diabetes who failed to maintain control of their glucose levels even after appropriate diet and physical activity for a period longer than or equal to a week. Other inclusion criteria included singleton pregnancy, the lack of risk factors for lactic acidosis, and the "absence of anatomic and/or chromosome anomalies of the conceptus." Patients who did not consistently follow-up with their physician for pre-natal visits were exempt from the study. The women who were eligible for the study were randomly placed in the metformin treatment group (n=47) or the insulin treatment group (n=47).
There was no significant difference of mean pretreatment glucose levels between the two different treatment groups. However, after each group started taking their medications, results showed that patients taking metformin contained significantly lower mean glucose levels than the insulin takers, mostly after dinnertime (P=0.02). Furthermore, women in the metformin group displayed less weight gain and hypoglycemia.
About 26% of the women in the metformin group required supplemental insulin since their blood glucose remained uncontrolled. The women who needed the supplemental insulin were typically younger and had higher mean pretreatment glucose levels. Hence, "early gestational age at diagnosis (odds ratio, 0.71; 95% confidence interval, 0.52–0.97; P = .032) and mean pretreatment glucose level (odds ratio, 1.061; 95% confidence interval, 1.001–1.124; P = .046) were identified as predictors of the need for insulin."
In conclusion, the authors of the study believe that metformin may be potentially used as a first-line treatment option for gestational diabetes in women. However, they mention the need for a similar study to be done with a "long-term follow-up."
Pavao C et al. Randomized trial of metformin vs insulin in the management of gestational diabetes. American Journal of Obstetrics & Gynecology. 2013; 209(1): 34.e1-34.e7.