7892 Longitudinal Changes in Bone Microarchitecture and Strength in Girls with Type 1 Diabetes
Authors: Dhaliwal R , Saunders R K , Misra M , Bouxsein M L , Mitchell D M 
Published: October 2024

Abstract
Disclosure: R. Dhaliwal: None. R.K. Saunders: None. M. Misra: None. M.L. Bouxsein: None. D.M. Mitchell: None.
Introduction: Type 1 diabetes (T1D) confers an increased fracture risk, only partly explained by low areal bone mineral density (aBMD). We have previously shown in a cross-sectional study that bone microarchitecture is altered early in the course of T1D. The goal of this study is to evaluate how T1D influences longitudinal changes in volumetric BMD (vBMD) and microarchitecture. Methods: This is a 2-year prospective study of girls ages 10-16 years (62 with T1D and 59 controls). We used dual-energy x-ray absorptiometry (DXA) to measure aBMD, and high-resolution peripheral quantitative computed tomography (HR-pQCT) at the distal radius (7% site) and tibia (8% site) to measure vBMD and microarchitecture. We used linear mixed models to assess the effects of T1D on change in bone parameters over time, adjusting for bone age as an index of skeletal maturity, height, lean mass index (LMI), and fat mass index (FMI). Results: At baseline, mean duration of disease in T1D was 4.8 ± 3.2 years, and mean HbA1c was 8.6 ± 1.4%. The groups did not differ by age, bone age, and height, while T1D participants had higher LMI (p&lt;0.001) and borderline higher FMI (p=0.107). Linear growth, weight gain, and changes in body composition over time did not differ between groups. Growth-mediated aBMD gains were observed in both groups at the subtotal body, total hip, femoral neck, and spine. While adjusted aBMD as well as trabecular bone score were lower in T1D, we did not observe between-group differences in changes in these endpoints over time. In both groups, at the distal radius, we observed significant increases over time in total and cortical vBMD, cortical thickness, trabecular (Tb) thickness, and estimated failure load, while cortical porosity decreased. While several microarchitectural parameters were altered in T1D participants, we did not observe significant between-group differences in changes in these measures over time. Of note, trabecular development was subtly altered, with T1D participants demonstrating a borderline significant decrease in Tb vBMD (-14.3 ± 9.0 mg HA/cm3, p=0.112) and Tb number (-0.14 ± 0.07 mm-[1], p=0.057), while control participants had no change in Tb vBMD or number, but a significant increase in Tb thickness (5.8 ± 2.5 µm, p=0.018). At the distal tibia, we observed similar overall detrimental effects of T1D at baseline. However, we did not observe between-group differences in microarchitectural change over time. Glycemic control as measured by HbA1c was not associated with changes in skeletal parameters among T1D participants. Conclusions: T1D leads to substantially altered areal and volumetric BMD as well as microarchitectural parameters in girls. While our data suggest that much of this deficit appears to occur early in the course of disease as prospective change is similar in T1D and controls, subtle changes in trabecular bone development at the radius may indicate ongoing impairment of bone accrual.
Presentation: 6/3/2024