The effects of diabetes mellitus and diabetic nephropathy on bone and mineral metabolism in T2DM patients

Aim: To assess the effects of both diabetes mellitus and diabetic nephropathy on bone mineral metabolism in patients with type 2 diabetes mellitus (T2DM). Methods: Serum osteocalcin (BGP), serum alkaline phosphatase (ALP), bone-specific alkaline phosphatase (BAP), 24-h urinary hydroxyproline (HOP), blood and urine calcium (Ca), phosphate (P) levels and bone mineral density (BMD) were assessed and compared in 30 patients with T2DM (group D), 25 T2DM patients with nephropathy (group DN) and 27 nondiabetic control subjects (group C). Results: Compared with the nondiabetic controls, patients in both groups D and DN had decreased serum osteocalcin (BGP) and bone mineral density (BMD) while serum alkaline phosphatase (ALP) and urinary hydroxyproline (HOP) were increased. Decrease in BGP was not correlated with ALP (r = -0.1, P < 0.37). Within both diabetes groups (group D and group DN), no significant change in BAP is observed, however group DN showed higher level of BGP, higher level of HOP and lower BMD than group D. Urine calcium was increased in both group D and DN with group D having higher levels than group DN. In DN patients had increased circulating phosphate and decreased urinary excretion of phosphate, while decreased circulating phosphate and increased urinary excretion phosphate are seen in group D patients. Conclusion: Patients with T2DM show an imbalance of bone mineral metabolism, and coexistence of nephropathy tends to aggravate this. Serum osteocalcin and 24-h hydroxyproline may be considered useful biochemical markers for monitoring possible bone mineral metabolism disorder in T2DM patients. (C) 2013 Elsevier Ireland Ltd. All rights reserved.