Background:Gestational diabetes mellitus (GDM) is a common obstetrical complication with both maternal and fetal side effects.Objective:This study was performed to determine the complications in neonates of mothers with GDM receiving insulin vs. dietary regimen.Materials and Methods:In this prospective cohort study, 140 neonates of mothers with GDM attending Javaheri Hospital of Azad University in Tehran in 2013 and 2014 were enrolled and the complications in those receiving insulin versus. dietary regimen were compared.Results:The results demonstrated that 95.7% of those who received a dietary regimen and 85.7% among those who received insulin had a good outcome showing statistically significant differences (p=0.042). The mortality rate was not differed among the patients in two groups (p>0.05).Conclusion:According to the results of this study, it may be concluded that the frequency of complications in neonates of cases with GDM is getting less by receiving dietary regimen.