Effects of metformin and insulin therapy regimens on postpartum oral glucose tolerance test results in pregnant women with gestational diabetes mellitus: a comparative study

OBJECTIVES The main purpose of this study was to compare the effects of two regimens of metformin and insulin therapy on postpartum oral glucose tolerance test (OGTT) results in pregnant women with gestational diabetes mellitus (GDM). METHODS In this single-blind randomized clinical trial (RCT), a total number of 60 pregnant women meeting the inclusion criteria were assigned to two groups with a randomized block design (RBD): insulin therapy (IT) group (30 patients) and metformin therapy (MT) group (30 patients). At baseline, the data were comprised of prenatal maternal age, gestational age, GDM diagnosis, and maternal weight/height. During the postpartum period, 5-cc blood samples were taken from the pregnant women concerned to analyze their fasting blood sugar (FBS) levels. Then, the patients were asked to come back four days and six weeks later after delivery to check the OGTT results. At six weeks postpartum, in addition to OGTT, the glycated hemoglobin (HbA1C) test was performed for all mothers. Finally, six weeks after delivery, these mothers were evaluated with regard to weight loss and body mass index (BMI). RESULTS Six weeks postpartum, the maternal weight and BMI significantly decreased in the MT group compared with the IT one, while there was no significant difference between both groups at baseline. On the fourth day, the OGTT results in the MT group were significantly lower in comparison with those in the IT group (p=0.012). At sixth weeks postpartum, the OGTT results were comparably lower in the MT group than those reported for the IT one; however, such a difference was not statistically significant (p=0.087). CONCLUSIONS According to the study results, metformin could be an effective and safe treatment for pregnant women suffering from GDM instead of insulin therapy.