Serum osteoprotegerin and tumor necrosis factor related apoptosis inducing-ligand (TRAIL) are elevated in type 2 diabetic patients with albuminuria and serum osteoprotegerin is independently associated with the severity of diabetic nephropathy

Osteoprotegerin (OPG) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) have recently been reported to be associated with diabetic nephropathy in an in vitro study. However, the literature regarding serum OPG and TRAIL in type 2 diabetes mellitus patients is scarce. To investigate the role of OPG/TRAIL in diabetic nephropathy, we measured the serum concentrations of OPG and TRAIL in type 2 diabetes mellitus patients with different stages of nephropathy by enzyme-linked immunosorbent assay. One hundred seventy-nine subjects with type 2 diabetes mellitus were studied and stratified according to urinary microalbumin and serum creatinine measurements. The serum concentrations of OPG and TRAIL were significantly elevated in patients with microalbuminuria (OPG, 2154.2 ± 922.1 pg/mL; TRAIL, 80.2 ± 24.1 pg/mL) and macroalbuminuria (OPG, 2251.5 ± 925.7 pg/mL; TRAIL, 88.1 ± 23.8 pg/mL) as compared with patients with normoalbuminuria (OPG, 1690.1 ± 627.2 pg/mL; TRAIL, 70.7 ± 23.3 pg/mL). Serum OPG and TRAIL levels were increased in parallel and were significantly associated with each other. Using multivariate stepwise regression analysis, serum OPG was found to be an independent factor associated with the severity of diabetic nephropathy. Our results suggested that serum OPG may be a marker for the severity of diabetic nephropathy. Further studies are necessary to investigate the role of elevated serum OPG in the pathogenesis of diabetic nephropathy.