Evaluation of the longitudinal change in carbohydrate metabolism in pregnant women with normal glucose tolerance should improve our understanding of carbohydrate metabolism in these women. The primary purpose of this study is to describe the changes in carbohydrate metabolism during pregnancy in apparently normal women. This study is designed to determine the pattern of fasting blood glucose and oral glucose response in healthy pregnant women, in whom blood glucose was measured in the fasting state and after oral glucose load in the 1st, 2nd and 3rd trimesters, at term and 12 weeks after delivery in the same subjects. Each patient gave her informed written consent. None of them had a history of impaired glucose tolerance. None had any other disease or were taking any medications (such as corticosteroids, anti-convulsants or warfarin sodium) that might affect glucose metabolism. Women who had multiple gestations or pregestational diabetes were excluded from the study. Subjects were also excluded if a first degree relative had type Idiabetes mellitus or received treatment for hyperglycemia. Women who had fasting blood glucose levels exceeding 105 mg/di in 1st trimester were excluded from the study because pregestational diabetes could not be ruled out; and women with elevated screening levels (at least 135 mg/di) were instructed to have the 3 hour oral GTT. Each patient subsequently delivered a healthy child at term without difficulty. In the present study the mean fasting blood glucose and the mean GCT levels are found to be increasing with an increase in BMI. Even in the non-pregnant state the mean fasting blood glucose and the mean GCT levels are found to be increasing with an increase in BMI and the effect of BMI seems to be greater in the fasting state compared to GCT results