Our study is a randomized, prospective, controlled trial, including the first 30 consecutive Caucasian gestational diabetes patients diagnosed,according the International Association of Diabetes and Pregnancy Study Group (IADPSG) panel criteria, from November 2013 in the Department of Obstetric and Gynecology of Messina University (ITALY). After an informed consent they will be randomly assigned to receive (n. 15) diet and folic acid (400 mcg per day) alone or (n. 15) diet, folic acid (400 mcg per day) and myo-inositol (2 g. twice a day)supplementation. The insulin sensitivity index (HOMA-IR) and the glycemic profile will be monitor by CGMS for each patient at GDM diagnosis and after 8 weeks of treatment The pregnant women who will delivery before the time treatment (8 weeks) or who need insulin will be excluded.