It was found that the increased OPG level in type 2 diabetes patients is not due to the onset of diabetes but the progression of disease.81 However, OPG and RANKL levels are not related to the risk of type 2 diabetes.82 Although osteoblasts secrete large amounts of OPG, the extensive expression of OPG in other organs makes it hard to determine whether bone-derived OPG affects β-cells directly. Here, TNFSF11 is linked to diabetes mellitus.