Erythrocyte sorbitol dehydrogenase activity in diabetic patients.

An increased polyol-pathway activity is implicated in the pathogenesis of some diabetic complications. Little is known about the sorbitol-dehydrogenase (SDH) activity in diabetic patients, although cataract is described in diabetes as well as in SDH deficiency. Therefore, we studied SDH activity and the relation with complications and with sorbitol accumulation in erythrocytes from 96 type 1 diabetics and 29 age- and sex-matched healthy subjects. When comparing these groups erythrocyte sorbitol (ERY-SOR) was significantly (P < 0.001) increased in the diabetic patients, but no difference in SDH could be demonstrated. In the diabetic patients ERY-SOR was predominantly related to the glycaemia (r = 0.37; P < 0.001). The SDH activity correlated with HbA1 (r = 0.20; P < 0.03). In diabetic patients with severe nephropathy the ERY-SOR value is no longer different from the control value. It was concluded that, in poor metabolic control the SDH activity is increased, which counteracts but does not prevent the sorbitol accumulation nor the genesis of complications. In patients with macroalbuminuria the ERY-SOR decreases to the normal range. Since SDH activity is similar in type 1 diabetics and controls the decreased ERY-SOR in this complication might be due to other metabolic pathways.