Diabetic kidney disease (DKD, also called diabetic nephropathy, DN) is the major cause of end-stage kidney disease (ESKD) in many countries and is associated with increased morbidity and mortality as compared to other causes of kidney disease. One of the pathological changes of DKD is the thickening of the glomerular basement membrane, mesangial expansion and proliferation. The presence of the glycosaminoglycan side chains of heparan sulfate proteoglycan, an important constituent of the glomerular basement membrane, is decreased in DKD proportionally to the increasing degree of proteinuria. Research on animals has suggested that heparin and related substances may prevent glomerular membrane thickening. However, it is not known whether heparin and related substances can prevent the onset of DKD and, therefore, be recommended for primary prevention of this condition.