The exact pathogenesis of diabetic neuropathy is unclear, with both metabolic and vascular factors having been implicated. Microvascular disease is possibly the initial event in the development of diabetic complications. Microvascular disease may play an important role in the causation and exacerbation of diabetic neuropathy. Histopathological studies have shown thickening of vessel walls, hyperplasia of capillary endothelial cells and increased plugging of vessels in neuropathic patients. Endothelial dysfunction is thought to be an important initiating factor for the development of these complications. Endothelial dysfunction is thought to develop as a consequence of changes in nitric oxide and cell adhesion molecules in the plasma of diabetic patients. L-arginine is an amino acid, which is the only source of NO in the body.