Clinical and metabolic outcomes in pregnant women at risk for gestational diabetes mellitus supplemented with myo-inositol: a secondary analysis from 3 RCTs

Background: Gestational diabetes mellitus is defined as carbohydrate intolerance that begins or is first recognized during pregnancy. Insulin sensitizing substances such as myo-inositol have been considered for the prevention of gestational diabetes mellitus and related complications. Objective: Because previous studies failed to show a clear reduction of gestational diabetes mellitus complications, the aim of this study was to evaluate clinical and metabolic outcomes in women who are at risk for gestational diabetes mellitus supplemented with myo-inositol since the first trimester. Study Design: A secondary analysis of databases from 3 randomized, controlled trials (595 women enrolled) in which women who were at risk for gestational diabetes mellitus (a parent with type 2 diabetes mellitus, obese, or overweight) were supplemented with myo-inositol (4 g/d) throughout pregnancy. Main measures were the rate of adverse clinical outcomes: macrosomia (birthweight, ≥4000 g), large-for-gestational-age babies (fetal growth, ≥90 percentile), fetal growth restriction (fetal growth, ≤3 percentile), preterm birth (delivery before week 37 since the last menstruation), gestational hypertension, and gestational diabetes mellitus. Results: A significant reduction was observed for preterm birth (10/291 [3.4%] vs 23/304 [7.6%]; P=.03), macrosomia (6/291 [2.1%] vs 16/304 [5.3%]; P=.04), Large-for-gestational-age babies (14/291 [4.8%] vs 27/304 [8.9%]; P=.04) with only a trend to significance for gestational hypertension (4/291 [1.4%] vs 12/304 [3.9%]; P=.07). Gestational diabetes mellitus diagnosis was also decreased when compared with the control group (32/291 [11.0%] vs 77/304 [25.3%]; P<.001). At univariate logistic regression analysis, myo-inositol treatment reduced the risk for preterm birth (odds ratio, 0.44; 95% confidence interval, 0.20–0.93), macrosomia (odds ratio, 0.38; 95% confidence interval, 0.14–0.98), and gestational diabetes mellitus diagnosis (odds ratio, 0.36; 95% confidence interval, 0.23–0.57). Conclusion: Myo-inositol treatment in early pregnancy is associated with a reduction in the rate of gestational diabetes mellitus and in the risk of preterm birth and macrosomia in women who are at risk for gestational diabetes mellitus