Correlation between body mass index, bone mineral density and trabecular bone score in patients with Type 2 diabetes

To investigate the relationship between body mass index (BMI) and areal bone mineral density (BMD) as well as trabecular bone score (TBS) in adults with type 2 diabetes mellitus (T2DM) and to determine whether age or sex modifies these relationships.

We retrospectively identified 762 community-dwelling adults aged ≥ 50 years (257 with T2DM and 505 non-diabetic controls) who underwent dual-energy X-ray absorptiometry at our centre between August 2023 and May 2024. Lumbar-spine and femoral-neck BMD as well as TBS were extracted. Associations were evaluated with Spearman's ρ and multiple linear regression, adjusting for age and sex.

In men, BMI, BMD and TBS did not differ between diabetic and non-diabetic participants in any age stratum (all P > 0.05). Women aged 50-60 y with T2DM exhibited higher LS-BMD but lower TBS than non-diabetic peers (both P < 0.05), indicating early dissociation between density and micro-architecture. Correlation analysis shows a positive association between BMI and LS-BMD (ρ=0.286, P= 0.002). Multivariate linear regression confirmed that BMI was an independent positive predictor of LS-BMD (β = 0.276, P < 0.001) and an independent negative predictor of TBS (β = -0.069, P = 0.043).

In T2DM, higher BMI is independently associated with greater BMD but poorer trabecular micro-architecture. This paradox is most evident in post-menopausal women, underscoring TBS as an early warning tool when BMD remains normal.