Quantitative ultrasound and vertebral fractures in patients with type 2 diabetes

Patients with type 2 diabetes (T2DM) are known to have increased risks of femoral neck and vertebral fractures, although their bone mineral density (BMD) is normal or even slightly increased compared to non-DM controls. This observation suggests that bone fragility not reflected by BMD, possibly deterioration of bone quality, may participate in their fracture risks. Quantitative ultrasound (QUS), unlike BMD, could possibly evaluate bone quality, especially the microarchitecture, and therefore may be useful for assessing fracture risk in T2DM. To test this hypothesis, we measured calcaneal QUS as well as BMD at the lumbar spine, femoral neck, and 1/3 radius in 96 women (mean age 66.6 years old) and 99 men (64.7 years old) with T2DM, and examined their associations with prevalent vertebral fractures (VFs). Calcaneal QUS was performed by CM-200 (Elk Corp., Osaka, Japan), and speed of sound (SOS) values were obtained. BMD was measured by QDR4500 (Hologic, Waltham, MA). In T2DM patients, VFs were found in 33 and 45 subjects in women and men, respectively. When compared between subjects with and without VFs, there were no significant differences in values of SOS or BMD at any site between the groups in either gender. The distribution of SOS as a function of age showed that those with VFs were scattered widely, and there were no SOS thresholds for VFs in either gender. Logistic regression analysis adjusted for age and BMI showed that either SOS or BMD was not significantly associated with the presence of VFs in either gender. These results show that QUS as well as BMD are unable to discriminate T2DM patients with prevalent VFs from those without VFs. It seems necessary to seek other imaging modalities or biochemical markers evaluating bone fragility and fracture risk in T2DM.