PROLONGED HYPOGLYCEMIA IN RESPONSE TO INTRAVENOUS TOLBUTAMIDE IN A PATIENT WITH LAENNEC'S CIRRHOSIS AND SEVERE MALNUTRITION

Diagnosis of pancreatic islet hyperplasia causing hypoglycemia in a patient with portacaval anastomosis

A patient with biopsy-proved biliary cirrhosis and previous gastrojejunostomy and portacaval anastomosis experienced episodes of severe hypoglycemia. She was found to have hyperinsulinemia and hyperglucagonemia. An oral glucose tolerance test showed postgastrectomy hypoglycemia. Results of the intravenous tolbutamide test were diagnostic for insulinoma, but results of the intravenous glucagon test and prolonged fast (96 hours) were not. Failure, on two occasions, to suppress C-peptide normally during insulin-induced hypoglycemia led to a diagnosis of pancreatogenous hyperinsulinemia. The pancreas showed a 10-fold increase in islet volume, with intensely positive staining with anti-insulin and anti-glucagon antiserums in addition to anti-somatostatin and anti-pancreatic polypeptide antiserums. Incidental findings at pancreatic exploration were a mesothelioma, which did not stain with anti-insulin antiserum, and, at autopsy one year later, a hepatoma.

Glucagon test for insulinoma: a chemical study in 25 cases

The capillary blood glucose response to lmg of intramuscular glucagon was determined in 13 patients with insulinoma and in 33 normal controls; the insulinoma patients showed a normal initial rise, but this was followed by an abnormally large fall, reaching hypoglycaemic levels between 90 and 180 minutes in every case. In 14 insulinoma patients the response of venous blood glucose and also plasma insulin to lmg of intravenous glucagon was compared with 10 normal controls; there was an abnormally large rise of plasma insulin in 10 of the 14 patients, and in the majority the venous blood glucose was below normal throughout the test. In these 14 patients the plasma insulin response was also determined after oral and intravenous glucose, after oral leucine, and after intravenous tolbutamide, and the value of these tests in the recognition and differential diagnosis of insulinoma was compared with that of the intravenous glucagon test.

MODIFICATION OF THE HYPOGLYCAEMIC RESPONSE TO TOLBUTAMIDE AND INSULIN BY MEBANAZINE--AN INHIBITOR OF MONOAMINE OXIDASE

Following reports of clinical changes in the carbohydrate metabolism of diabetic patients receiving mebanazine, possible interactions between mebanazine, adrenaline, tolbutamide and insulin have been studied in rats. Mebanazine had no activity on blood sugar levels and was found to have no effect on the metabolic actions of injected adrenaline. In acute experiments, mebanazine appeared to reduce the net hypoglycaemic action of tolbutamide but had no effect on the response to insulin. In chronic experiments, mebanazine pre-treatment led to a significant potentiation of the hypoglycaemic responses both to tolbutamide and insulin. The possible mechanisms of action and the clinical implications are discussed.