To evaluate efficacy of metformin in comparison to insulin for managing GDM. Methods. In prospective randomized comparative study, 150 antenatal women whose pregnancies had been complicated by GDM and did not respond to diet alone were recruited from antenatal clinics at Obstetrics Department in Zagazig University Hospitals from November 2012 to December 2014. The gene discussed is INS; the disease is gestational diabetes.