Characterization of the insulin resistance of glucose utilization in adipocytes from patients with hyper- and hypothyroidism

Insulin action on glucose utilization was characterized in adipocytes from 10 thyrotoxic patients, 6 hypothyroid patients and 10 age- and sex-matched control subjects. In thyrotoxic patients insulin binding at low insulin concentrations was reduced (P less than 0.05) and accompanied by impaired insulin sensitivity of glucose transport (P less than 0.02), glucose oxidation (P less than 0.05) and lipogenesis (P less than 0.05). Glucose transport and glucose oxidation rates also exhibited depressed maximal insulin responsiveness (P less than 0.05). In hypothyroid patients insulin binding was reduced, too, (P less than 0.05) and associated with impaired sensitivity to insulin of glucose transport (P less than 0.05). Both glucose transport and lipogenesis rates showed decreased maximal insulin responsiveness (P less than 0.05). In conclusion: In man, both hyper- and hypothyroidism are characterized by insulin resistance of adipocyte glucose utilization localized to insulin binding as well as to insulin-stimulated glucose transport and metabolism.