Late complications such as retinopathy and neuropathy contribute substantially to the morbidity of patients with diabetes mellitus but have only moderate effect on their life expectancy. However, once diabetic nephropathy occurs, life expectancy of patients with diabetes mellitus is shortened considerably. This review discusses briefly several possible pathogenetic mechanisms involved in the development of diabetic nephropathy. Changes in renal hemodynamics as the initiating and contributing factor to the development of diabetic nephropathy are discussed in more detail. Finally, the article reviews possible therapeutic measures to prevent the development of diabetic nephropathy, or to slow down its progression.