Increased insulin responsiveness and insulin clearance in thyrotoxicosis.

The euglycemic insulin clamp technique was used to evaluate in vivo insulin action in thyrotoxicosis (TTX). Insulin was infused at 0.5, 3 and 10 mu/kg per min, and the steady-state glucose infusion rate was determined in five TTX patients with fasting hyperinsulinemia and five healthy subjects. TTX is accompanied by a significant increase in insulin responsiveness, clearance and basal insulin delivery rate. Therefore, insulin resistance in TTX does not reside at the postreceptor peripheral tissue level, but may be the consequence of increased hepatic glucose production.