The Effect of Myo-Inositol Supplementation During Pregnancy on Fetal and Maternal Outcomes: Results of the Myo-Inositol for the Prevention of Gestational Diabetes Mellitus (MiGDM) Randomized Double-Blind, Placebo-Controlled Pilot Trial

Gestational diabetes mellitus (GDM) is a common pregnancy complication with significant maternal and neonatal risks, and its prevalence is particularly high in Qatar. Myo-inositol has been proposed as an insulin-sensitizing supplement that may reduce the incidence of GDM, but evidence is limited in this population. This study aims to evaluate the effect of antenatal dietary myo-inositol supplementation on the incidence of GDM among pregnant women in Qatar and to assess the impact on fetal and neonatal outcomes. Sidra Medicine, Qatar, conducted this prospective, randomized, double-blind, placebo-controlled pilot trial (2022-2023). The trial was registered with International Standard Randomised Controlled Trial Number (ISRCTN; protocol number ISRCTN16448440) and approved by the Institutional Review Board of Sidra Medicine (IRB Number: 1538656). Only 67 pregnant women were recruited, and 43 of them finished the trial till birth, despite the study's initial power to enrol 640 pregnant women (320 each group). This was due to funding-related early discontinuation. Eligible women were ≤16 weeks of gestation, planned to deliver at the study center, and had no pre-gestational diabetes. Participants were randomized to receive either myo-inositol supplementation (2 g twice daily) or a placebo until delivery. Data collection included maternal demographics, anthropometric measurements, and pregnancy and neonatal outcomes. The primary outcome was the incidence of GDM diagnosed by oral glucose tolerance test in both groups. Secondary outcomes included pregnancy and neonatal outcomes, along with predictors of insulin resistance (Homeostasis Model Assessment of β-cell function (HOMA B; %) and Homeostatic Model Assessment of Insulin Resistance (HOMA IR; index)). Although the study concluded before reaching target recruitment due to funding challenges, an analysis of the cumulative data was performed. Sixty-seven pregnant women were recruited, and 43 patients completed the study until delivery. There were 18 patients in the myo-inositol group and 25 in the placebo group. No significant difference was observed between the two groups in the incidence of GDM. Additionally, there were no significant differences between the two groups in the measures of insulin resistance (HOMA B or HOMA IR) and maternal and neonatal outcomes. Dividing the study population into those who developed GDM (16 patients) versus those who did not develop GDM (27 patients) revealed significantly higher fasting insulin levels (12.65 ± 7.29 µIU/mL vs 7.37 ± 3.24 µIU/mL, p=0.027) and increased insulin resistance measured by HOMA IR (3.05 ± 1.82 vs 1.54 ± 0.69, p=0.010) in the GDM group compared to the non-GDM group. However, there was no significant difference in HOMA B between the two groups. The GDM group had a lower gestational age at delivery (37.8 ± 3.89 weeks vs 39.21 ± 0.57 weeks, p=0.03) than the non-GDM group. There was no statistically significant difference in the incidence of GDM or the outcomes for mothers and newborns between the myo-inositol and placebo groups in this severely underpowered sample. This study was unable to definitively evaluate the original hypothesis due to the significant recruitment deficit and consequent lack of statistical power. Therefore, the results should be regarded as inconclusive, and we are unable to draw clear conclusions about the effectiveness of myo-inositol supplementation.