Effectiveness of Metformin in the Prevention of Gestational Diabetes Mellitus in Obese Pregnant Women

Abstract Objective To assess the effectiveness of metformin in the incidence of gestational diabetes mellitus (GDM) in obese pregnant women attending a public maternity hospital in Joinville, Santa Catarina, Brazil. Methods Randomized clinical trial including obese pregnant women with a body mass index (BMI) ≥ 30 kg/m2, divided into two groups (control and metformin). Both groups received guidance regarding diet and physical exercise. The participants were assessed at two moments, the first at enrollment (gestational age ≤ 20) and the second at gestational weeks 24-28. The outcomes assessed were BMI and gestational diabetes mellitus (GDM) diagnosis. The data distribution was assessed with the Friedman test. For all the analytical models, the p-values were considered significant when lower than 0.05. The absolute risk reduction was also estimated. Results Overall, 164 pregnant women were assessed and further divided into 82 participants per group. No significant difference was observed in BMI variation between the control and metformin groups (0.9 ± 1.2 versus 1.0 ± 0.9, respectively, p = 0.63). Gestational diabetes mellitus was diagnosed in 15.9% (n = 13) of the patients allocated to the metformin group and 19.5% (n = 16) of those in the control group (p = 0.683). The absolute risk reduction was 3.6 (95% confidence interval 8.0- 15.32) in the group treated with metformin, which was not significant. Conclusion Metformin was not effective in reducing BMI and preventing GDM in obese pregnant women.

摘要 研究目的
旨在评估二甲双胍对巴西圣卡塔琳娜州若因维利市某公立妇产医院就诊的肥胖孕妇妊娠期糖尿病（GDM）发病率的影响。
方法
本研究为随机临床试验，纳入体重指数（BMI）≥30 kg/m²的肥胖孕妇，随机分为对照组与二甲双胍组。两组均接受饮食与运动指导。研究对象分别于两个时间点接受评估：首次为入组时（孕周≤20周），第二次为孕24~28周。评估结局指标包括BMI及GDM诊断结果。采用弗里德曼检验评估数据分布情况。所有分析模型均以P<0.05为差异具有统计学意义的判定标准。同时估算了绝对风险降低值。
结果
最终共纳入164名孕妇，每组各82人。对照组与二甲双胍组的BMI变化值无显著差异（分别为0.9±1.2与1.0±0.9，P=0.63）。二甲双胍组15.9%（n=13）的孕妇确诊GDM，对照组为19.5%（n=16），组间差异无统计学意义（P=0.683）。二甲双胍组的绝对风险降低值为3.6（95%置信区间：8.0~15.32），该结果无统计学意义。
结论
二甲双胍无法降低肥胖孕妇的BMI水平，亦无法预防GDM的发生。