The Prevention of Gestational Diabetes Mellitus With Antenatal Oral Inositol Supplementation: A Randomized Controlled Trial

Randomized, parallel-group, single-center trial in Ireland enrolling pregnant women at their first antenatal visit who were at increased risk of gestational diabetes because of a family history of diabetes. In the inositol plus folate arm, 120 participants were randomized at 10-16 weeks' gestation; the study site was a tertiary referral center.

Pregnant participants in the active arm received an oral inositol regimen started at the first antenatal visit (10-16 weeks' gestation): myo-inositol 1,100 mg daily plus D-chiro-inositol 27.6 g daily, together with folic acid 400 mcg daily. The product was Inofolic Combi and it was taken once daily until delivery, compared with folic acid alone in the control arm.

The inositol plus folate regimen did not prevent gestational diabetes. Gestational diabetes occurred in 23.3% (28/120) of the intervention group versus 18.3% (22/120) of controls, P = 0.34, and fasting glucose was 81 mg/dL in both groups at the OGTT; 1-hour glucose was 138.6 vs 133.2 mg/dL (P = 0.42) and 2-hour glucose was 102.6 vs 97.2 mg/dL (P = 0.07). Most maternal and neonatal outcomes were similar, including birth weight, caesarean delivery, and NICU admission. Neonatal hypoglycemia was more frequent with inositol plus folate (9 [8%] vs 1 [1%], P = 0.01), and the authors concluded this dose should not be used routinely in antenatal supplementation.

Only one inositol dose and timing strategy was tested, so the findings do not exclude benefit from higher or different dosing. The study was single-center with a modest sample size, limiting power for less common maternal and neonatal outcomes and generalizability beyond this at-risk Irish population. Several secondary outcomes were based on 117 participants per arm rather than the full randomized sample.