Carbohydrate metabolism in pregnancy. XII. The effect of oral glucose on plasma concentrations of human placental lactogen and chorionic gonadotropin during late pregnancy in normal subjects and gestational diabetics

During late pregnancy, minor, although significant, reductions of plasma human placental lactogen (HPL) were observed 30 and 60 min following oral administration of 100 g glucose to subjects with normal carbohydrate metabolism or gestational diabetes. When data for the 2 groups were pooled, the integrated net changes in serum glucose during 180 min ('glucose area') correlated significantly with the HPL decrements at 60 min. Concurrent monitoring of plasma concentrations of human chorionic gonadotropin (HCG) disclosed a similar trend. However, whereas significant reductions of plasma HCG were evident 60 min following oral glucose administration in the normal subjects, the decrements did not achieve statistical significance at any time in the gestational diabetics. Some of the acute and transitory changes in placental hormones following oral glucose administration could have metabolic implications. Insofar as HPL may exert contrainsulin and lipolytic properties, even minor reductions in the concentration of HPL, to which maternal tissues are exposed, could facilitate anabolism in the immediate period following glucose ingestion. On the other hand, information about the action of HCG on intermediary metabolism is insufficient to justify speculation concerning the possible metabolic consequences of glucose related changes in plasma HCG.