A study aimed at demonstrating that administration of d-chiro inositol and folic acid from the first trimester of pregnancy counteracts the onset of gestational diabetes mellitus in women at risk, and prevents the incidence of macrosomia, hypoglycemia and preterm delivery. A total of 40 women were treated with d‑chiro‑inositol, d‑myo‑inositol, zinc, methylsulfonyl-methane, and 5‑methyltetrahydrofolic acid. On the other hand, the control group was administered only folic acid. It was reported that the incidence of maternal gestational diabetes mellitus was 18 in the control group and 5 in the treated group at the 24^th week of pregnancy. Moreover, there was a significant difference between treated and control groups with regard to the risk of macrosomia. The researchers thus concluded that administration of d-chiro-inositol and d-myo-inositol may be beneficial for pregnant-at risk women, with first trimester fasting plasma glucose levels over 92 mg/dl.