Introduction : 2-5% of pregnancies are complicated by diabetes, of which 90% are classified as gestational diabetes mellitus' Aims find objectives : To analyst,' the screening & diagnostic procedure for GDM recommended by ADA in comparison with the WHO criteria To study the outcome of GDM diagnosed by both the criteria. Materials and methods : This prospective study was carried out in the Department of O&G JIPMER between September 2006 and June 2006. 350 antenatal cases of yestational age 24 weeks .attending' outpatient department, with any one of the risk factors for GDM were included in the study'. 75g oral GTT performed Results were interpreted using both ADA and WHO criteria .