[Blood glucose and insulin responses to oral glucose in hyperthyroidism]

Because thyroid hyperfunction "per sè" can induce impaired glucose tolerance in 2-57% of patients, we have studied glycaemic and insulinaemic response to oral glucose load (OGTT) in this condition. Glycaemic and insulinaemic curves after oral glucose (100 g), the respective secretory areas (AUC-G and AUC-IRI) have been determined in 13 hyperthyroid patients (8 Graves disease, 4 multinodular toxic goiters and 1 Plummer's adenoma) and in 16 healthy control subjects. AUC-G, AUC-IRI and median values of G and IRI in most of considered times have resulted significantly greater in hyperthyroid patients. This study has confirmed the impact of thyroid hyperfunction on carbohydrate metabolism, but has not proved an impaired insulin secretion as previously reported in Literature. In conclusion, we believe that: a) hyperthyroidism is associated with greater circulating levels of G and IRI, b) hyperinsulinaemia in addition to hyperglycaemia suggests that insulin-resistance is underlying in this condition.