Abstract 71: Assessment of skeletal microarchitecture by high resolution peripheral quantitative computed tomography (HR-pQCT) in patients with type 1 diabetes

Background: Type 1 diabetes mellitus (T1D) is characterized by autoimmune destruction of pancreatic β- cells with consequent absolute insulin deficiency and hyperglycemia. Adult patients with T1D have a sixfold increased fracture risk. However, this increase in fracture risk in T1D patients could not be explained by BMD alone. As far as skeletal microarchitecture in T1D is concerned, data is sparse in world literature and absent in Indian population. Hence, we aimed to study the skeletal microarchitecture in T1D subjects as assessed by High Resolution Peripheral Quantitative Computed Tomography (HR-pQCT) and compared these parameters with age, sex and BMI matched controls. Methods: We recruited 31 T1D cases without celiac disease (Group A: Male15, Female 16), 11 T1D cases with celiac disease (Group B: Male 5, Female 6) and 19 age, sex and BMI matched healthy control (Group C: Male 10, Female 9). Blood biochemistry and hormonal profile including calcium profile, 25(OH) vitamin D, iPTH and HbA1C level between the Group A and B were compared. The HR-pQCT parameters among the three groups were also compared. Results: The median age of male and female participants in Group A [22 (20-25) years and 23 (22-26) years], Group B [26 (22-31) and 23 (21-24) years] and Group C [27 (18-28) years and 26 (25-27) years] were comparable. BMI was also comparable between the three groups. The duration of diabetes, insulin dose per kg body weight, calcium profile, 25(OH) vitamin DandiPTH level were similar between Group A and B. Median HbA1C value in male and female subjects within Group A and B were 7.05 (6.4-8.0)% and 8.2 (7.2-10.2) %, 8.2 (6.4-9.6) %, and 9.2 (7.9-12.3) %, respectively; and when sex specific comparison was done, the differences were statistically insignificant. Radial cortical vBMD (volumetric BMD) was significantly higher in male subjects in Group B as compared to male cases in Group C. Tibial trabecular vBMD in female participants was significantly lower in Group B as compared to Group C. Tibial trabecular bone volume fraction in female was greater in Group C as compared to the other groups. Trabecular thickness in femaletibiawas also greater in Group C compared to other two groups; while, trabecular thickness of female radius was higher in Group C compared to Group A. Conclusions: Skeletal microarchitecture is altered in T1D subjects with and without celiac disease. This may explain higher skeletal fragility in this subgroup of patients.