In particular, women treated with myo-inositol showed a significantly lower prevalence of GDM in mid-pregnancy (risk ratio (RR) = 0.127, 95% CI [0.032–0.502], P = 0,001), required less insulin therapy (RR = 0.136, 95% CI [0.018–1.031], P = 0.053), delivered at a later gestational age (95% CI [− 2.578 to − 0.948], P = 0.001), and had significantly smaller babies (birth weight is expressed as percentiles, 95% CI [10.807–30.116], P = 0.001) with fewer episodes of neonatal hypoglycemia (RR = 0.052, 95% CI [0.003–0.849], P = 0.038) compared to placebo. This evidence concerns the gene INS and gestational diabetes.