SOME EFFECTS OF ORAL CONTRACEPTIVES ON CARBOHYDRATE METABOLISM

Abstract

Abstract Longitudinal studies of plasma glucose, non-esterified fatty acids (N.E.F.A.), and insulin and blood-pyruvate levels during oral and intravenous glucose-tolerance tests are described in three groups of women treated with combined oral contraceptive preparations: (A) 91 women tested before and during therapy, (B) 39 women tested during therapy and again after this had been discontinued, and (C) 22 women tested twice during therapy. The mean fasting plasma-glucose was unchanged during therapy. In terms of the total area between the plasma-glucose curve and the abscissa, oral and intravenous glucose tolerance deteriorated during therapy in 78% and 70% of group-A women, respectively. 13% of group-A women developed chemical diabetes mellitus during therapy. In group B, oral glucose tolerance improved in 90% and intravenous glucose tolerance improved in 85% after therapy was discontinued. Group C, with initial mean oral glucose tolerance similar to that of group B during therapy, showed no significant mean change of oral glucose tolerance on retesting. Mean plasma-N.E.F.A. levels, both before and after oral or intravenous glucose, were unchanged during therapy in groups A and B. During therapy the mean fasting blood-pyruvate was elevated in group A and mean blood-pyruvate levels were also higher in both groups during oral and intravenous glucose-tolerance tests. The mean fasting plasma-insulin levels were unchanged during therapy in both groups, but significant elevation of plasma-insulin levels occurred in group A after oral and intravenous glucose. Mean plasma-insulin levels during oral and intravenous glucose-tolerance tests in group B, however, were not significantly different on and off therapy. It is suggested that the impaired glucose tolerance is steroid diabetes caused by elevated plasmacortisol (hydrocortisone) levels secondary to the oestrogen component of the oral contraceptive. The clinical consequences of these abnormalities remain to be determined.