Monitoring of diabetic late complication.

Secondary symptoms of long-lasting diabetes mellitus are diabetic neuropathy with sensory symptoms, motoric disturbances due to reduced nerve conduction velocity, and diabetic cataracts. Both are related to enhanced conversion of glucose to polyols, such as sorbitol, by the enzyme aldose reductase (van Heyningen 1959; Clements 1979). Sorbitol is converted to fructose by sorbitol dehydrogenase. A low activity of this enzyme enhances the accumulation of sorbitol, thus contributing to cellular damage. Inhibitors of aldose reductase have been developed with positive results in diabetic patients (Kador et al. 1985)