Plasma Insulin and Glucagon Responses to Arginine in Patients with Thyroid Dysfunction

Plasma insulin and glucagon responses to l-arginine were compared in normal subjects and patients with hyper- and hypothyroidism. Hyperthyroid patients were characterized by low plasma insulin response and almost normal plasma glucagon response, whereas hypothyroid patients showed high insulin and glucagon responses. The impaired insulin response to l-arginine in the case of hyperthyroidism was significantly improved after thyroid function was normalized by treatment.