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.