ENZYMATIC, METABOLIC AND SECRETORY PATTERNS IN HUMAN ISLETS OF TYPE-2 (NON-INSULIN-DEPENDENT) DIABETIC-PATIENTS

Islets were isolated by automatic digestion from non-diabetic cadaveric organ donors and from Type 2 (non-insulin-dependent) diabetic subjects. The activity of FAD-glycerophosphate dehydrogenase, but not that of either glutamate dehydrogenase, glutamate-oxalacetate transaminase or glutamate-pyruvate transaminase, was lower in Type 2 diabetic patients than control subjects. Hexokinase, glucokinase and glutamate decarboxylase activities were also measured in islets from control subjects. The utilization of D-[5-H-3]glucose, oxidation of D-[6-C-14]glucose and release of insulin evoked by D-glucose were all lower in Type 2 diabetic patients than control subjects. The secretory response to the combination of L-leucine and L-glutammine appeared less severely affected. Islets from Type 2 diabetic patients may thus display enzymatic, metabolic and secretory anomalies similar to those often observed in animal models of Type 2 diabetes, including a deficiency of beta-cell FAD-linked glycerophosphate dehydrogenase, the key enzyme of the glycerol phosphate shuttle.