Carbohydrate metabolism in porphyria cutanea tarda.

A study on carbohydrate metabolism (glycaemia and insulinaemia curves during the oral and the intravenous glucose tolerance tests) in 20 porphyria cutanea tarda patients revealed diabetes mellitus in 2 and impaired glucose tolerance in 1 patient, but the carbohydrate tolerance did not differ greatly from that of matched controls. The porphyria cutanea tarda patients, instead, had a significantly exaggerated insulin response, which was more marked in patients with liver disorders. It is proposed that the hyperinsulinism is secondary to the liver damage.