[Updates on Lifestyle-Related Diseases and Bone Metabolism. Increase in bone fragility from the viewpoint of bone structural properties].

Diabetes mellitus (DM) and chronic renal disease (CKD) show the dissociation between their bone mineral density (BMD) and their fracture risk. High-resolution peripheral computed tomography (HR-pQCT) contributes to investigate the deterioration of structural properties in these diseases. In type2 DM, the increase in cortical porosity account for its high fracture risk. In CKD, parathyroid hormone (PTH) is anabolic in trabecular bone and catabolic in cortical bone, which produces complicated bone feature. If hyperparathyroidism is severe, cortical thinning and increased cortical porosity appear in the compact bone, and irregular thickened trabeculae and dissecting intra-trabecular resorption appear in the cancellous bone. Even in the early stage of CKD, the bone microstructural changes are observed. For further investigation of the structural changes in relation to biomechanical properties in type2 DM and CKD, the longitudinal studies are required using in vivo HR-pQCT.