Glucose turnover and gluconeogenesis in a patient with somatostatinoma

Previous evidence has documented the hyperglycemia and glucose intolerance that occur during prolonged infusions of somatostatin and in patients with somatostatinoma. We studied glucose utilization and production and gluconeogenesis (from alanine) in a patient with the somatostatinoma syndrome (peripheral somatostatin levels 20,000 pg/ml) during saline (basal state) and glucose infusion (1.78 mg/kg . min). Plasma glucose levels increased from 163 to 229 mg/100 ml during glucose infusion, whereas lactate, free fatty acid, and glucagon levels did not change. Endogenous glucose production decreased from 7.34 to 0.0 mumol/kg . min, and the percentage of glucose derived from alanine also decreased from 10.5 to 7.4. Glucose clearance decreased from 0.81 to 0.74 cc/kg . min and suggests that the hyperglycemia of the somatostatinoma syndrome is secondary to reduced peripheral glucose utilization secondary to relative insulin deficiency.