Background: Although it is well established that subjects with type 2 diabetes (T2D) have an increased fracture risk, there have been conflicting reports on the relationship of T2D to bone mineral density (BMD). Such discrepancies could be due to failure to adjust for potential confounding factors which could influence BMD.
Objectives: To assess the relationship between type 2 diabetes and BMD at the femoral neck and spine in diabetic and non-diabetic subjects, after adjusting for multiple covariates which are known, or suspected to, affect BMD. Intervertebral disc height was also investigated in view of its possible relation to fracture risk.
Methods: A hundred patients with type 2 diabetes of at least 5 years duration (mean age 63 years) and 86 non-diabetic subjects (mean age 59 years) were recruited. A cross-sectional study was carried out whereby BMD T-scores and disc heights between the twelfth thoracic (T12) and the third lumbar (L3) were compared between the two study groups.
Results: There was a higher spine BMD T-score on monovariate analysis (mean±S.D. 0.08±1.2 vs −0.29±1.24; P=0.049 respectively) in diabetic subjects. However, there were no significant differences in T scores in either the spine or femoral neck after adjustment for potential confounding variables between T2D subjects and controls. Diabetic patients had a statistically lower intervertebral disc height between the 2nd and third lumbar vertebrae when compared to controls both on monovariate analysis as well as after adjustment for potential confounders (mean adjusted difference of 0.028 cm, P=0.02).
Conclusion: We found that diabetes exerts no significant independent effect on BMD. However, there was significantly lower disc height in patients with T2D. This may contribute to the increased vertebral fracture risk in subjects with T2D. Further studies need to be carried out in order to try and further assess the relationship between BMD, disc height and T2DM.