Diabetes has become a major public health problem in China, and a large-scale epidemiological survey revealed a prevalence of 9.7% approximately 5 years ago [1]. Diabetic nephropathy (DN) is the most common microvascular complication and is a major cause of end-stage renal disease that requires dialysis and/or renal transplantation [2]. Thus, strategies aimed at the treatment of DN are as important as those that target diabetes itself. Diabetic nephropathy is associated with mesangial cell expansion, thickening of glomerular and tubular basement membrane, glomerulosclerosis and tubular necrosis. These structural changes could lead to the occurrence of albuminuria, elevation of serum creatinine and urea nitrogen levels, and reduction in glomerular filtration rate[3].