β-CTX, as an expression of the carboxy-terminal peptide of Type-I collagen, can reflect osteoclast activity.15 In the early stage of diabetic nephropathy, especially when there is no significant change in BMD, the bone synthesis indexes such as BGP and T-PINP will decrease, and the level of osteolysis index β-CTX will increase. The gene discussed is BGLAP; the disease is diabetic kidney disease.