Diabetes causes increased oxidative stress, which is thought to play an important role in the
pathogenesis of various diabetic complications. However, the source of the hyperglycemia-
induced oxidative stress is not clear. It was found that the polyol pathway is the major
contributor to oxidative stress in the lenses and nerves of diabetic mice. The first enzyme in
the pathway, aldose reductase (AR), reduces glucose to sorbitol, which is then converted to
fructose by sorbitol dehydrogenase (SDH). Transgenic mice that overexpress AR specifically …