Gestational diabetes mellitus (GDM) is a disorder of carbohydrate metabolism, that develops due to inability to compensate for physiological increase in insulin resistance in pregnancy and is associated with adverse maternal and perinatal outcomes. To measure the maternal and neonatal outcomes of Gestations diabetes Mellitus (GDM) using World Health Organization (WHO) versus International Association of Diabetes in Pregnancy Study Group (IADPSG) criteria among pregnant mother. The current study had been conducted in the department of obstetrics &gynaecology in COMJNMH HOSPITAL, KALYANI, West Bengal during. 500 women were screened for eligibility. Among them 200women were diagnosed GDM of whom 155 women fulfilled IADPSG criteria and45women were selected on the basis of WHO criteria. Prevalence of Gestational diabetes was 31% and 9% respectively using IADPSG and WHO (1999) criteria. The current study revealed that there was no statistically significant difference between both the groups in relation to pre–eclampsia and mode of delivery. But lower segment caesarean section (LSCS) increased in both groups. Birth weight of neonates were between 2.7–2.8 kgs. in majority of neonates of women of both groups. The mean birth weight was significantly higher in the neonates of diagnosed by WHO criteria than those women diagnosed by IADPSG criteria (mean 2.8kgs vs 2.5 kgs in respectively WHO & IADPSG, p=0.015). In our study, neonatal hypoglycemia & neonatal hypocalcemia was infrequent in either group. Neonatal hypoglycemia detected 6.5% and 8.9% and neonatal hypocalcemia detected 1.9% and 4.4% in respectively IADPSG and WHO group. Although, there was no significant difference statistically among the two groups, both hypoglycaemia and hypocalcaemia was more evident in the newborns of mothers detected by WHO critera. It can be concluded that, overall, maternal outcome did not show any major benefit in IADPSG group. Neonatal outcome parameters were marginally better in the IADPSG group