Endothelial NO synthase (eNOS) activity is an important vascular modulator which is altered in diabetes, and functionally significant polymorphisms of the eNOS (NOS3) with lower production of NO [23]–[25] are associated with the development of nephropathy in patients with type 1 and type 2 diabetes [26]–[28]. The gene discussed is NOS3; the disease is kidney disorder.