Height-for-age adjusted bone mineral density and associated factors in youth with type 1 diabetes

Bone fragility is a known complication of type 1 diabetes (T1D) and because DXA provides areal rather than volumetric bone mineral density (BMD), height-for-age adjustment offers a more accurate assessment of bone density.

To evaluate HAZ-adjusted BMD z-scores (BMD z-scores adjusted for height-for-age [HAZ]) in youth with T1D and identify factors associated with height-adjusted bone density.

This cross-sectional study included youth aged 8-17 years with T1D ≥1 year underwent DXA; T1D-related history, anthropometrics, dietary intake, and 25-hydroxyvitamin D [25(OH)D] were analyzed in association with HAZ-adjusted BMD z-scores.

A total of 124 youth participated (mean age 12.9 ± 2.5 years; BMI z-score 0.67 ± 0.81; HAZ 0.25 ± 0.96; diabetes duration 6.0 ± 3.2 years; HbA1c 8.1 ± 1.1%). Mean daily intake was 8.7 ± 9.0 μg vitamin D, 1011.1 ± 464.7 mg calcium, and 1.5 ± 0.6 g/kg/day protein; recommended dietary allowance targets were met by 17%, 23%, and 85%, respectively. Vitamin D status was 9% deficient, 48% insufficient, and 43% sufficient. Mean HAZ-adjusted BMD z-score was -0.36 ± 1.01, significantly lower than the reference data (p = 0.0001). BMD z-scores correlated with BMI z-scores (r = 0.27, p = 0.002) and 25(OH)D (r = 0.25, p = 0.005). The vitamin D-deficient group had significantly lower HAZ-adjusted BMD z-scores than both the insufficient and sufficient groups (Δ = 1.06, p = 0.004; Δ = 1.02, p = 0.004). No associations were observed with diabetes duration, HbA1c, or dietary intake of vitamin D, calcium, or protein.

Youth with T1D had lower HAZ-adjusted BMD compared with the reference population, and HAZ-adjusted BMD was associated with BMI z-scores and 25(OH)D levels. Maintaining healthy weight and adequate vitamin D levels remains important for bone health in this population.