Insulin and C-peptide in ascitic fluid and plasma and their relative responses to glucagon in patients with cirrhosis.

Insulin (IRI) and C-peptide dynamics were studied after iv glucagon in 5 nondiabetic patients with ascites due to cirrhosis of the liver. Plasma and ascitic fluid samples for glucose, IRI and C-peptide determinations were obtained before and 6, 10, 15, 20 and 30 min after glucagon injection. Ascitic fluid volumes, estimated by dilution of ip injected PAH, were 6.2 to 20.5 L. The mean fasting plasma glucose [88 +/- 6.7 mg/dl (SE)] and C-peptide (1.40 +/- 0.42 ng/ml) levels were normal; mean plasma insulin was increased (17.4 +/- 3.0 microU/ml). After glucagon injection, there was a subnormal rise in plasma glucose (PG) compared to 5 mild diabetic patients without liver disease (8.4 +/- 3.5 vs 76 +/- 7.4 mg/dl). The plasma C-peptide rise was less than that of plasma IRI (54% vs 192%). The mean basal ascitic fluid concentration of glucose was 86 +/- 9.4 mg/dl, IRI 13.2 +/- 2.9 microU/ml and C-peptide 3.09 +/- 0.49 ng/ml. Total calculated basal ascitic fluid contents of glucose was 5.2-23.3 g, IRI 47, 120-290,000 microU and C-peptide 15,750-66,420 ng. These were 3-10 times the quantity of these substances circulating in the plasma volume. After glucagon injection, there was no significant increase in ascitic fluid glucose or IRI, but there was a 43% increase in C-peptide concentration at 10 min. In ascitic fluid, the molar concentration of IRI was lower and C-peptide higher than plasma, resulting in a C-peptide: IRI molar ratio of 11.31, markedly higher than the published normal plasma ratio of 4.63.(ABSTRACT TRUNCATED AT 250 WORDS)