Metabolic profiles in patients with insulinoma

Twelve-hour metabolic profiles have been measured in six patients with insulinoma and results compared with normal subjects of similar age and weight. Fasting blood glucose was lower (mean +/- SEM 2.9 +/- 0.3 mmol/l vs 5.0 +/- 0.2 mmol/l) and plasma insulin higher (20.0 +/- 3.9 mU/l vs 7.2 +/- 1.6 mU/l) in insulinoma patients. Over the 12-h period blood glucose, pyruvate and glycerol were significantly lower, and plasma insulin, blood lactate, alanine and plasma non-esterified fatty acids (NEFA) significantly higher in insulinoma patients. Overall the concentration of blood total ketone bodies was significantly higher in insulinoma patients. Values were higher in the early part of the day but lower later in the day and did not show the marked pre-meal rise observed in the normal subjects. The raised NEFA and ketone bodies are of particular interest as they may be a source of fuel supply in the presence of relative glucose deficiency.