Changes in the Effects of Insulin on Human Adipose Tissue Metabolism in Hyperthyroidism*

The in vitro effects of insulin on glycerol release and glucose incorporation into neutral lipids (lipogenesis) were studied in segments of sc adipose tissue obtained from 9 control subjects and 11 patients with hyperthyroidism; 6 patients were reinvestigated after treatment. In untreated hyperthyroidism, there was a decreased sensitivity to the antilipolytic effect of insulin, since the dose-response curve was shifted to the right; 250 microU/ml insulin were required for 50% of the maximal effect compared to 25 microU/ml in the controls. During antithyroid therapy, the dose-response curve normalized. Insulin caused a 25% increase in lipogenesis in the untreated hyperthyroid patients, but no consistent effect was seen in the control subject or in hyperthyroid patients during treatment.