Effects of Oral and Intravenous Glucose Loading in Thyrotoxicosis: Studies of Plasma Glucose, Free Fatty Acid, Plasma Insulin and Blood Pyruvate Levels

Abstract

Plasma glucose, NEFA, insulin and blood pyruvate levels before and after oral/intravenous glucose administration have been compared in a group of twenty-eight thyrotoxic subjects and a group of control subjects matched for age, sex and degree of obesity. The mean fasting plasma glucose level was elevated, and 44 per cent of oral and 24 per cent of intravenous glucose tolerance tests were impaired in the thyrotoxic group. The mean plasma insulin level in the thyrotoxic group was elevated both before and after oral and intravenous glucose administration. Mean fasting plasma NEFA levels were elevated in the thyrotoxic group but fell to normal levels following glucose administration. Mean fasting blood pyruvate levels were similar in control and thyrotoxic groups but abnormally elevated levels were observed in the latter following oral glucose administration. Mean fasting serum triglyceride levels were similar in both groups, but the mean fasting serum cholesterol was significantly lower in the thyrotoxic subjects. The possible significance of these abnormalities is discussed.