FAD-GLYCEROPHOSPHATE DEHYDROGENASE-ACTIVITY IN LYMPHOCYTES OF TYPE-2 DIABETIC-PATIENTS AND THEIR RELATIVES

The activities of FAD-linked glycerophosphate dehydrogenase (m-GDH), g lutamate dehydrogenase (GlDH), glutamate-pyruvate transaminase (GPT) a nd glutamate-oxalacetate transaminase (GOT) were measured in purified populations of CD3 + lymphocytes from 55 control subjects, 62 type-2 d iabetics and 50 non-diabetic relatives of the latter patients. The act ivity of m-GDH was measured by both a radioisotopic procedure and colo urimetric technique. As judged from these measurements and relative to the paired value for GlDH, the incidence of abnormally low m-GDH acti vity was significantly higher in type-2 diabetics than in control subj ects. Moreover, the paired ratio in reaction velocity between the colo urimetric and radioisotopic assay of m-GDH was abnormally high in pati ents with low m-GDH activity. Low m-GDH activity often coincided with increased GPT activity in plasma or high GPT/GOT ratio in lymphocytes, No obvious clustering of these anomalies was found in relatives of di abetic patients. These findings suggest that an inherited or acquired genomic defect of m-GDH in lymphocytes, and possibly in pancreatic B-c ells, may participate to the pathogenesis of non-insulin-dependent dia betes mellitus.