Diagnostic criteria of diabetic neuropathy that can be easily used at bedsides and have international consensus have not been established. The most important therapeutic strategy is to maintain strict glycemic control. In addition, treatment with an aldose reductase inhibitor that is innovated from the viewpoint of the pathogenesis of diabetic neuropathy would be useful for preventing the progression of diabetic neuropathy. For painful diabetic neuropathy, pregabalin and duloxetine effectively relieve the pain, and contribute to the improvement of the quality of life.