Effects of spontaneous portal-systemic shunting on insulin metabolism.
Insulin degradation was measured by the C-peptide/insulin ratio in 19 patients with portal vein block with extensive spontaneous portal-systemic shunting but minimal liver cell damage: 13 patients with biopsy-proved cirrhosis and 12 controls. Blood obtained fasting and for 3 hr after oral glucose was assayed for glucose, insulin, and C-peptide. Fasting C-peptide and insulin levels in patients with portal vein block and those in controls did not differ. Eight of 13 cirrhotic patients had fasting hyperinsulinemia with a significantly reduced C-peptide/insulin ratio. After glucose administration, the C-peptide/insulin ratio in portal vein block patients with normal aspartate transaminase levels did not differ from control values. In portal vein block patients with elevated asparatate transaminase levels, the C-peptide/insulin ratio was significantly reduced only from 60 min onwards. All the cirrhotic patients showed a significantly reduced C-peptide/insulin ratio after glucose administration. It is suggested that portal-systemic shunting of blood in the presence of a normal liver does not influence hepatic insulin metabolism and that the hyperinsulinemia of cirrhosis is a feature of parenchymal liver damage. In addition, insulin degradation was abnormal in all cirrhotic patients at high insulin secretion rates, even when fasting insulin levels were normal.
D000293:Adolescent; D000328:Adult; D000368:Aged; D001219:Aspartate Aminotransferases / Q000097:blood; D001786:Blood Glucose / Q000032:analysis; D002096:C-Peptide / Q000097:blood; D003251:Constriction, Pathologic; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood*; D008103:Liver Cirrhosis / Q000097:blood / Q000201:enzymology; D008297:Male; D008875:Middle Aged; D011169:Portal Vein; D013927:Thrombosis / Q000097:blood* / Q000201:enzymology
D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D001219:Aspartate Aminotransferases