[Variations of the coefficient of glucose assimilation in normal pregnancy]

Three hundred eleven intravenous glucose tolerance tests were performed in normal pregnant women between the 8th and the 40th week, and compared with similar tests performed in two groups of non-pregnant women, one group on oral contraceptives, the other not. There was a relative improvement in glucose tolerance at the beginning of pregnancy followed by marked loss of tolerance after the 24th week. This evolution is due to the physiologic adaptation of the maternal pancreas to fetal and placental metabolism. The range of normality for the glucose disappearance rate differs before and after the 24th week of pregnancy, and this must be recognised in setting diagnostic criteria for gestational diabetes. Consideration of simultaneous studies of glucose tolerance and insulin secretion at various periods of pregnancy suggests that changes in K value are more closely correlated with variations in peripheral insulin effects than with changes in insulin secretory function of the maternal pancreas.