Objective : According to Pederson hypothesis, fetal hyperinsulinism is the major cause for adverse neonatal outcome. The aim was to determine the association between cord blood insulin (CBI) levels with neonatal outcome and maternal glycemic control in gestational diabetes mellitus (GDM). Method : Prospective study. A total of 184 mothers were studied; 92 belonged to GDM group and 92 to non GDM group. Cord blood was collected from umbilical vein soon after delivery and insulin levels were determined using radioimmunoassay. GDM group was divided into two subsets based on CBI (Subset A < 20uU/ml and Subset B > 20uU/ml).