Hypoinsulinemia of Hypothyroidism

To understand carbohydrate intolerance of hypothyroidism, glucose and insulin responsiveness was studied in eight patients before and after treatment. A striking early hypoinsulinemia in response to intravenously administered glucose has been observed. Fasting levels of plasma glucose and serum insulin were normal and remained unchanged after treatment, while glucose disappearance rates were significantly improved following therapy (P<05). During hypothyroidism, substantial insulin release was not detected until four minutes after onset of glucose infusion, and the mean maximal response was not achieved until six minutes. In contrast, despite identical glucose levels during the first seven minutes, the euthyroid state was associated with a prompt rise at three minutes, reaching maximal insulin response at four or five minutes. These results indicate that hypothyroidism is characterized by diminution of the acute insulin response, similar to that observed in some patients with maturity-onset diabetes, which may be responsible for the impaired glucose tolerance observed