Large-scale clinical trials revealed that poor glycemic control in the early stage of diabetes exerts long-lasting detrimental effects on kidney function. We think that abnormalities in epigenetics underlie memory phenomenon of diabetic kidney disease. We found that persistent overexpression of detrimental factors is accompanied by aberrant DNA methylation in the kidney of diabetic mice (J Am Soc Nephrol 2015). We are studying DNA methylation of human kidneys obtained from diabetic patients aiming at new therapy. Urine DNA methylation may be useful for early diagnosis.