Skeletal Fragility & Its Clinical Determinants In Children With Type 1 Diabetes.

CONTEXT: Type 1 diabetes (T1D) is associated with an increased fracture risk at all ages.

OBJECTIVE: To understand the determinants of bone health and fractures in children with T1D.

DESIGN: Case-control study of children with T1D on bone turnover markers, DXA and 3T-MRI of the proximal tibia to assess bone microarchitecture and vertebral marrow adiposity, compared to age and sex-matched healthy children.

RESULTS: 32 children with T1D at a median (range) age of 13.7 years (10.4,16.7) and 26 controls aged 13.8 years (10.2,17.8) were recruited. In children with T1D, serum BAP SDS, CTX SDS, and total body and lumbar spine BMD SDS were lower (all p<0.05). Children with T1D also had lower trabecular volume [0.55 (0.47,0.63) vs 0.59 (0.47,0.63); p=0.024], lower trabecular number [1.67 (1.56,1.93) vs 1.82 (1.56,1.99); p=0.004] and higher trabecular separation [0.27 (0.21,0.32) vs 0.24 (0.20,0.33); p=0.001] than controls. Marrow adiposity was similar in both groups (p=0.25). Bone formation as assessed by BAP was lower in children with poorer glycemic control (p=0.009) and who were acidotic at initial presentation (p=0.017) but higher in children on continuous subcutaneous insulin infusion (p=0.025). Fractures were more likely to be encountered in children with T1D compared to controls [31% vs 19%; p<0.001]. Compared to those without fractures, the T1D children with a fracture history had poorer glycemic control (p=0.007) and lower total body BMD (p<0.001) but no differences in bone microarchitecture.

CONCLUSION: Children with T1D display a low bone turnover state with reduced bone mineralisation and poorer bone microarchitecture.