Metformin and glyburide are both as effective as insulin in the management of gestational diabetes, a meta-analysis of randomized clinical trials has found, though their risk profiles differ.
The investigators looked at 18 trials comparing the two oral agents with insulin, and in some cases with each other, in about 2,800 women with gestational diabetes.
The study showed significant differences among the oral drugs and insulin in maternal fasting blood glucose or glycosylated hemoglobin levels, suggesting that all are effective in controlling GDM, according to Dr. Yun-fa Jiang of Hebei Medical University in Shijiazhuang, China, and associates (J. Clin. Endocrinol. Metab. [doi:10.1210/jc.2014-4403]).
However, compared with insulin, metformin was associated with lower maternal weight gain (weighted mean difference: –1.49 kg; 95% confidence interval, –2.26 to 0.31), and shorter gestational age (WMD, –0.16 kg/week; 95% CI, –0.30 to –0.03). Glyburide was associated with higher neonatal birth weight (130.68 g; 95% CI, 55.98 to 205.38), neonatal hypoglycemia (odds ratio, 2.64; 95% CI, 1.59 to 4.38), and increased incidence of macrosomia (OR, 3.09; 95% CI, 1.59 to 6.04) compared with insulin. In a network meta-analysis, metformin was seen associated with significantly less maternal weight gain, compared with glyburide (WMD, –1.34; 95% CI, –3.05 to 0.38; P = .009).
The differences might be attributable to different mechanisms of action in the two oral drugs, according to the investigators, who noted that this was the first network meta-analysis comparing efficacy and safety of oral antidiabetics in management of gestational diabetes. “There exists some apprehension regarding the use of oral antidiabetic drugs during pregnancy,” they wrote. “While no long-term harms to the exposed offspring from either of these drugs have been demonstrated, no long-term studies have been performed with appropriate controls, either in humans or animal models.”
Dr. Jiang and colleagues noted among the weaknesses of their study the relatively few trials included, and that blinding was not possible in trials that compared oral agents with insulin therapy.
The study was funded by China’s National Science Foundation and none of its authors declared conflicts of interest.