Bone mineral density and fracture risk in patients with type 1 and type 2 diabetes mellitus

Abstract

Diabetes affects an estimated 6-8% of the population worldwide. This widespread disorder is often associated with changes in bone health which are still little studied. To date, there has been no generally accepted definition of diabetic osteopathy. The changes in the bone mineral density, the bone turnover markers and frequency and type of fractures that occur in the two major clinical types of diabetes (type 1 and type 2) differ because they are associated with different pathogenetic mechanisms inducing these disorders. While it is reduction of the bone mineral density that most often occurs in type 1 diabetes, in type 2 diabetes various studies diagnose either a normal, reduced or increased bone mineral density in comparison with that of healthy controls. Both vertebral and non-vertebral fractures are found to have increased incidence in both types of diabetes which is attributed to, in addition to the changes in the mineral density of bones, a number of concomitant factors such as visual impairment, diabetic neuropathy, etc. There are studies demonstrating that women with type 1 diabetes are at a significantly higher risk of hip fractures (relative risk [RR]: 8.9 [95% confidence interval (CI): 1.2-64.4]) and for those with type 2 diabetes: (RR: 2.0 [95% CI: 1.12-1.35]). The mortality rate in the first year after a patient sustains a fracture of the neck of the femur in men is about 36%, and in women--about 21%. The changes in the bone mineral density in diabetes are caused by a number of disorders--negative calcium balance, hypoinsulinemia, deteriorated renal function, increased production of advanced glycation end products, low peak bone mass, increased production of inflammatory cytokines, etc.

Conclusions: Although there are differences in the quantitative changes of bone mineral density, patients with diabetes mellitus have a higher risk of sustaining specific types of fractures. It can be partially accounted for by the greater propensity to falling, as well as to the decreased bone toughness caused not only by the quantitative changes but also by the altered bone quality. Diabetics with additional osteoporosis predisposing risk factors or with current fractures should have their bone density measured and then receive a relevant prophylactic treatment.