Objective: To identify the effects of different dietary inositol stereoisomers on insulin resistance and the development of gestational diabetes mellitus (GDM) in women at high risk for this disorder.Design: A preliminary, prospective, randomized, placebo controlled clinical trial.Participants: Nonobese singleton pregnant women with an elevated fasting glucose in the first or early second trimester were studied throughout pregnancy.Intervention: Supplementation with myo-inositol, d-chiro-inositol, combined myo- and d-chiro-inositol or placebo.Main outcome measure: Development of GDM on a 75 grams oral glucose tolerance test at 24-28 weeks' gestation. Secondary outcome measures were increase in BMI, need for maternal insulin therapy, macrosomia, polyhydramnios, neonatal birthweight and hypoglycemia.Results: The group of women allocated to receive myo-inositol alone had a lower incidence of abnormal oral glucose tolerance test (OGTT). Nine women in the control group (C), one of the myo-inositol (MI), five in d-chiro-inositol (DCI), three in the myo-inositol/D-chiro-inositol group (MI/DCI) required insulin (p = .134). Basal, 1-hour, and 2 hours glycemic controls were significantly lower in exposed groups (p < .001, .011, and .037, respectively). The relative risk reduction related to primary outcome was 0.083, 0.559, and 0.621 for MI, DCI, and MI/DCI groups.Conclusions: This study compared the different inositol stereoisomers in pregnancy to prevent GDM. Noninferiority analysis demonstrated the largest benefit in the myo-inositol group. The relevance of our findings is mainly related to the possibility of an effective approach in GDM. Our study confirmed the efficacy of inositol supplementation in pregnant women at risk for GDM.
Keywords: d-chiro-inositol; gestational diabetes mellitus; myo-inositol.