Comparison of maternal and fetal outcomes in women with gestational diabetes treated with metformin versus insulin: an open-label randomized clinical trial

Abstract

Background: Pregnancies complicated by gestational diabetes are associated with an increased risk of adverse maternal and fetal outcomes.Objectives: This trial aimed to compare maternal and fetal outcomes in Iranian women with gestational diabetes treated with either metformin or insulin.Methods: In this open-label randomized clinical trial, eligible Iranian women referred to Shohada-e-Tajrish Hospital (Tehran, Iran) between January and September 2022 were enrolled through simple random sampling. Participants were randomly assigned to two groups: one receiving metformin (n=50) and the other receiving insulin (n=49). We measured HbA1c, fasting plasma glucose (FPG), and 2-hour plasma glucose (2 hrPG) in all participants. Maternal outcomes, including preeclampsia and cesarean delivery rates, were compared alongside neonatal outcomes such as respiratory distress, congenital disorders, small for gestational age (SGA), macrosomia, birth weight, gestational age at birth, shoulder dystocia, hypocalcemia, hypoglycemia, Apgar scores at 5 minutes, and neonatal intensive care unit (NICU) admissions. Data analysis was performed using SPSS 16 with t-tests, Mann-Whitney U tests, Chi-square tests, or Fisher's exact tests as appropriate.Results: Both metformin and insulin demonstrated similar efficacy in controlling FPG, 2-hrPG, and HbA1c levels in women with gestational diabetes (P>0.05). In the metformin group, there were slightly more cases of respiratory distress (P=0.73) and cesarean deliveries (P=0.35), although these differences were not statistically significant. Conversely, the insulin group showed higher, yet not statistically significant, rates of preeclampsia (P=0.70), congenital disorders (P=0.07), small for gestational age (SGA) infants (P=0.48), shoulder dystocia (P=0.31), hypocalcemia (P=0.31), hypoglycemia (P=0.31), and NICU admissions (P=0.21). Macrosomia, average birth weight, and gestational age at birth were similar between the two groups (P>0.05). The only significant finding was that the average Apgar score at 5 minutes was significantly higher in the metformin group compared to the insulin group (P=0.003). No mortality was reported in either group.Conclusion: The findings of this study indicate that metformin has effects comparable to those of insulin regarding maternal and neonatal outcomes in Iranian women with gestational diabetes.

Keywords

• gestational diabetes
• metformin
• insulin