1. Responses to a 50 g oral glucose load and intravenous administration of 1 g of sodium tolbutamide have been compared in thirteen patients with hepatocellular carcinoma and ten control subjects.
2. The hepatoma patients have lower basal plasma glucose and immunoreactive insulin concentrations. Plasma insulin responses to glucose and tolbutamide are impaired whether considered as the absolute concentrations or related to the plasma glucose concentrations as an insulinogenic index.
3. Hepatoma patients also demonstrate increased endogenous insulin sensitivity and hypoglycaemic unresponsiveness as shown by a greater and more sustained fall in glucose concentration following intravenous administration of tolbutamide.
4. Basal growth hormone concentrations are within the normal range and do not rise paradoxically after glucose administration.
5. These findings in hepatoma patients strikingly contrast with those seen in uncomplicated cirrhosis. The same phenomena are observed whether or not background cirrhosis is present with hepatoma and suggest that the tumour may be secreting a principle that suppresses hepatic gluconeogenesis and/or enhances glucose utilization. The principle is not immunoreactive insulin, but may be other unidentified substances elaborated by the tumour which produce the insulin-like effect.