In recent years, diabetic nephropathy, which may lead to dialysis treatment, is the most prevalent underlying disease of people in developed countries. A wide range of studies have been carried out, from various points of view, to understand the progress of renal dysfunction in diabetic nephropathy. The endogenous nitric oxide synthase (NOS) inhibitor asymmetric dimethylarginine (ADMA) is elevated in patients with chronic kidney disease (CKD) and may have a role in the cardiovascular mortality and morbidity of these patients. In diabetic nephropathy, high ADMA levels were related to progression of diabetic nephropathy.