Effects of an aldose reductase inhibitor on erythrocyte fructose 3-phosphate and sorbitol 3-phosphate levels in diabetic patients.

Fructose 3-phosphate and sorbitol 3-phosphate are novel metabolites that have been shown to associate with the polyol pathway in animal experiments. Fructose 3-phosphate is of particular interest because of its potent glycation capability as compared with other glycolytic intermediates, e.g., fructose. We observed the effects of treatment with epalrestat, an aldose reductase inhibitor, on their concentrations in erythrocytes from diabetic patients. The levels of both metabolites were significantly higher in diabetic patients than in non-diabetic subjects. A group of patients who had been treated with epalrestat showed significantly lower levels of both metabolites as compared with those untreated. A treatment of three patients with epalrestat for one month resulted in obvious decreases in their concentrations. The results suggest a possible explanation for the preventive effect of an aldose reductase inhibitor on nonenzymatic glycation.