The effect of myo-inositol supplementation on gestational diabetes mellitus prevention: a systematic review and meta-analysis

To assess the effectiveness of myo-inositol supplementation during pregnancy or the preconception period in preventing gestational diabetes mellitus among women without preexisting diabetes.

Comprehensive searches were performed in PubMed, Web of Science, Scopus, the Cochrane Database of Systematic Reviews, and ClinicalTrials.gov from inception through April 2025.

Randomized controlled trials enrolling women without preexisting diabetes, either pregnant or planning conception within 6 months, were included. Eligible studies compared myo-inositol supplementation with placebo or standard care.

Random-effects meta-analyses were conducted to calculate pooled relative risks and 95% confidence intervals. Heterogeneity was quantified with the I2 statistic. Sensitivity analyses, including leave-one-out testing, were performed to evaluate the influence of individual studies. Risk of bias was evaluated using the Cochrane Handbook criteria.

Twelve randomized controlled trials comprising 4765 women met inclusion criteria. Most trials were of moderate to high quality, with some concerns regarding bias. Myo-inositol supplementation substantially reduced the risk of gestational diabetes mellitus compared with control groups, corresponding to a 44% risk reduction. No significant differences were observed in secondary maternal outcomes, including hypertensive disorders and cesarean delivery, or neonatal outcomes such as macrosomia, preterm birth, and neonatal hypoglycemia.

Myo-inositol supplementation in pregnancy or preconception lowers the risk of gestational diabetes mellitus in women without preexisting diabetes. These findings support myo-inositol as a promising, safe, and accessible preventive strategy for gestational diabetes and reinforce its potential role in improving maternal metabolic health.