Glucagon and insulin metabolism in cirrhotic patients.

BACKGROUND/AIMS: The aim of this study was to investigate glucagon and insulin metabolism in order to clarify the mechanisms that lead to hyperglucagonemia and hyperinsulinemia in cirrhosis.

METHODOLOGY

Splanchnic output and metabolic clearance rates were studied in 16 cirrhotic patients and 5 non-cirrhotic controls. Splanchnic glucagon and insulin output into the portal circulation were calculated by the difference between portal venous and systemic arterial concentration multiplied by portal plasma flow. The metabolic clearance rate was calculated as the ratio of output to systemic arterial concentration. Portal blood flow was measured by continuous local thermodilution.

RESULTS

Arterial glucagon levels were higher in cirrhotics than in controls. Glucagon output was triple of that found in controls (52.4 +/- 7.0 vs 17.7 +/- 2.9 ng/min, p < 0.05). Both groups exhibited similar metabolic clearance rates of glucagon. Systemic arterial insulin values were higher in cirrhotics than in non-cirrhotics. Insulin output was not significantly different between the two groups. However, metabolic clearance of insulin in cirrhotics was reduced to one half of the rate found in controls (237.0 +/- 39.8 vs. 450.5 +/- 17.5 mL/min, p < 0.05).

CONCLUSIONS

Hyperglucagonemia in cirrhotic patients results from increased pancreatic output, while hyperinsulinemia results from decreased insulin clearance.