Insulin and C-peptide in chronic liver diseases during oral glucose tolerance testing

Abstract

Insulin and C-peptide in venous blood were determined during oral glucose tolerance testing in 59 non-manifest diabetics with histologically established chronic liver disease (fatty degeneration, chronic aggressive hepatitis, cirrhosis). Glucose tolerance was pathologic in 60-80% of patients. When compared to a control group patients with chronic liver disease showed significantly increased values of blood glucose (after glucose intake), of insulin and of C-peptide (fasting and after glucose intake). The C-peptide/insulin ratio, a measure of hepatic insulin degradation, was significantly decreased after glucose uptake. There were no significant differences of blood sugar, insulin and C-peptide among the various liver diseases. In chronic aggressive hepatitis and in cirrhosis the C-peptide/insulin ratio was partly significantly lower than in fatty degeneration. From the increased C-peptide values increased insulin secretion in chronic liver diseases can be deducted. In addition, the decreased C-peptide/insulin ratios show an impairment of insulin degradation in liver cirrhosis and other chronic hepatic diseases. However, in fatty liver degeneration this is clearly less pronounced than in more serious liver diseases.