Bone metabolism and fracture risk in type 2 diabetes mellitus

Osteoporosis and type 2 diabetes mellitus (T2DM), both prevalent in aging and westernized societies, adversely affect the health of elderly people by causing fractures and vascular complications, respectively. Recent experimental and clinical studies show that the disorders are etiologically related through the actions of osteocalcin and adiponectin. Meta-analyses of multiple clinical studies show that the hip fracture risk of T2DM patients is increased 1.4-1.7-fold compared with non-DM controls, even though the patients' bone mineral density (BMD) is not diminished. Vertebral fracture risk of the T2DM patients is also increased, and BMD measurement is not sensitive enough to assess this risk. These findings suggest that bone fragility in T2DM patients depends on bone quality deterioration rather than bone mass reduction. Surrogate markers are therefore needed to supplement the partial effectiveness of BMD testing in assessing the fracture risk of the T2DM patients. Markers related to advanced glycation end products may be candidates. These substances modulate bone quality in DM. Until research establishes the usefulness of surrogate markers, physicians should assess fracture risk in T2DM patients not only by measuring the BMD, but also by taking a fracture history and evaluating prior vertebral fractures using spinal X-rays.