Gestational diabetes mellitus (GDM) is the most common metabolic abnormality during gestation. Gestational diabetes mellitus is defined as abnormal glucose tolerance was 25% in lean women and 50% in obese women compared with a 5-10% prevalence in a control population. Women attending the Obstetrics & Gynecology outpatient department of the Govt. Medical College, were interviewed and from many volunteers 31 were selected as being in good general health, of average build, free from any family history of diabetes, and were sure of their last menstrual dates. Each patient gave her informed written consent. None of them had a history of impaired glucose tolerance. The mean (± SD) fasting plasma glucose levels during the 1st, 2nd and 3rc1 trimester and at term were 69.9 ± 9.2 mg/di, 71.7 ± 7.5 mg/di, 75 .9 ±8.3 mg/di, and 76.8 ± 8.5 mg/di respectively. And the mean fasting plasma glucose in the non-pregnant state is 71.5 ± 7.2 mg/di. The mean (± SD) blood glucose values 1 hour after ingestion of 50 g oral glucose load (GCT) were 98.9 ± 15.2 mg/di, 105.3 ± 14.5 mg/di, 105.2 ± 13.7 & 104.9 ± 11.6 mg/di during the 1st,2nd and 3rd trimesters and at term respectively.