Carbohydrate metabolism in porphyria

A high proportion of patients with porphyria cutanea tarda (PCT) show a hyp erinsulinemic response to the oral glucose tolerance test (OGTT) attributed to the hepatopathy also frequent in this disease. We propose that hyperins ulinemia is the main feature and source of carbohydrate metabolic alteratio ns present in both chronic and acute types of porphyria. In order to verify this hypothesis, the insulinemic response to the OGTT was studied in 12 he althy controls, 18 PCT patients and 14 patients with acute types of porphyr ia. Of the PCT patients, 22% showed an altered response to the OGTT, in agr eement with other authors. The frequency of altered hyperinsulinemic respon se in PCT patients was similar to that in acute-type porphyria patients. Ho wever, the intensity of this alteration was significantly higher in PCT tha n in acute-type porphyria patients. Among the PCT patients with hyperinsuli nemic response, some showed evidence of hepatic damage, while others did no t. On the other hand, patients with acute types of porphyria and chronic he patic damage, demonstrated by histology procedures, did not show the hyperi nsulinemic phenomenon. In summary, both PCT and acute-type porphyria patien ts show a higher frequency of hyperinsulinemic response to the OGTT than th e general population. This hyperinsulinemic response cannot be attributed t o concomitant hepatic damage, but hepatopathy can intensify the insulinemic response. Copyright (C) 2000 John Wiley & Sons, Ltd.