Moreover, in addition to mitochondria, other cellular ROS generating pathways, including cytosolic NOXs [25], xanthine oxidase (XO) [46], uncoupled endothelial NOS [47], myeloperoxidase (MPO) [48], cycloxygenase-2 [49], and endoplasmic reticulum stress [50] (Figure 3) also contribute to the pathogenesis of diabetic complications, including DN [51], neuropathy [52], and atherosclerosis [48]. This evidence concerns the gene XDH and neuropathy.