Cortical Bone Size Deficit in Adult Patients With Type 1 Diabetes Mellitus

Context: The increased fracture risk associated with type 1 diabetes mellitus (T1DM) remains unexplained by traditional risk factors such as low areal bone mineral density (aBMD). Nonetheless, few data exist on other determinants of bone strength in T1DM, including volumetric bone mineral density (vBMD) and bone geometry. Objective: Wecompared areal and volumetric bone parameters and cortical bone geometry in adult T1DM patients and sex-and age-matched controls. Design: Cross-sectional study including 64 adult T1DM patients (38 men; mean age, 41.168.1 years) and 63 sex-and age-matched controls. Main Outcome Measures: Areal bone parameters using dual-energy X-ray absorptiometry; volumetric bone parameters and cortic al bone geometry using peripheral quantitative computed tomography. Results: T1DM was associated with lower aBMD at the total body, femoral neck, and total hip; lower trabecular vBMD at the distal radius; and higher cortical but lower total vBMD at the radial shaft. In addition, subjects with T1DM had a similar periosteal but larger endosteal circumference, smaller cortical thickness, and lower cortical over total bone area ratio. Differences in bone parameters could not be explained by differences in bone turnover markers or body composition, but cortical area was inversely associated with glycemic variability and long-term glycemic control. Conclusions: Besides decreased aBMD and trabecular vBMD, adult T1DM patients present with a cortical bone size deficit, which may contribute to their increased fracture risk. This deficit is mainly situated at the endosteal envelope, suggesting imbalanced remodeling rather than compromised modeling processes as the underlying mechanism.