In this randomized single blind clinical trial, the efficacy of metformin with insulin for glycemic control and obstetrical complications in gestational diabetes mellitus are compared. Total 160 women 18 to 40 years with singleton pregnancy and gestational age between 20 to 34 weeks without underlying systemic disease with a diagnosis of GDM based on 2 or more abnormal values in 100 g oral glucose tolerance test (GTT) are studied. Women who failed diet therapy after one week with exist of two times (FBS> 95 mg / dl, BS> 120 mg / dl) were recruited randomly to receive either metformin (n=80) or insulin therapy (n=80) after getting a written consent .In the case group, metformin was given at a dose of 500 mg two times a day to a maximum of 2500 mg/day based on glycemic profile. In the control group, Insulin was started and titrated based on plasma glucose values. The goal of therapy is to have fasting glucose level <95 mg/dL and 2 hours postprandial level<120mg/dL.In the metformin group, insulin is added with two abnormal glucose profiles during the two weeks after reaching the maximum dose.
Secondary outcomes are included maternal and fetal prognosis. Maternal outcomes are including preeclampsia, gestational hypertension, preterm delivery and cesarean section. Fetal and neonatal prognosis including mortality, macrosomia, LGA, SGA, hypoglycemia, Hyperbilirubinemia, hypocalcaemia, birth trauma, respiratory distress and NICU admission.