Neuropathy, womens' health, and socioeconomic aspects of diabetes.

Abstract

This is the eighth and final in a series of reports on the American Diabetes Association (ADA) 61st Scientific Sessions in Philadelphia, PA, in June, 2001. At a symposium on neuropathy sponsored by the University of Texas Southwestern at the American Diabetes Association meeting in San Antonio, Texas, Soroku Yagihashi (Hirosaki, Japan) discussed aspects of the pathogenesis of distal symmetric polyneuropathy. In a recent survey in Tohoku, Japan, of 32,955 individuals with diabetes, history or symptoms of neuropathy made it the most common complication, occurring in 27% of patients. There are two major histologic findings in nerve biopsy from patients with distal symmetric polyneuropathy. Myelinated fiber density decreases, falling by approximately one-third with mild neuropathy and by two-thirds with severe neuropathy, reflecting loss of nerve fibers with degeneration of remaining fibers. There is also evidence of microangiopathy in the vasa nervosum. Nerve capillary density again decreases in proportion to the severity of the neuropathy, with capillary basement membrane area nearly doubled with mild neuropathy and tripled with severe neuropathy. The susceptibility of peripheral nerve to ischemia may be partly related to its great axon length with sparse blood supply. As with retinopathy and nephropathy, poor glycemic control is a major cause of neuropathy, with nerves not showing insulin-mediated glucose uptake, but rather allowing direct glucose entry, which increases with hyperglycemia. In the Tohoku survey, the likelihood of neuropathy increased 2.7-, 1.7-, and 1.2-fold in individuals whose HbA1c was ≥10, 7.5–9.9, and 6.5–7.49%, in comparison to those with HbA1c <6.5%. In the nerve, glucose is metabolized through the polyol pathway to sorbitol via the enzyme aldose reductase (AR). Sorbitol can cause osmotic stress and can lower nerve myoinositol and taurine levels, with decreases in Na+/K+-ATPase, which is involved in intracellular energy homeostasis. In addition, conversion …