Prevalence and determinants of “TBS worse than BMD” discordance in older type 2 diabetic adults: findings from the Bushehr Elderly Health (BEH) program

Abstract Although individuals having type 2 diabetes mellitus (T2DM) are generally at increased risk for osteoporosis and fractures, they paradoxically tend to exhibit relatively higher bone mineral density BMD T-scores. The trabecular bone score (TBS) has been shown to better gauge bone health in these patients, frequently revealing deterioration that BMD fails to detect. This study aims to investigate the prevalence and determinants of the “TBS worse than BMD” discordance among T2DM patients aged 50 years and older in Iran. This study was based on the data from the first phase of the second recruitment of the Bushehr Elderly Health (BEH) program. Dual-energy x-ray absorptiometry (DXA, Discovery WI Bone Densitometer; Hologic, Bedford, MA, USA) was used for BMD measurement, and TBS iNsight software (version 2.2; Medimaps Group, Plan-les-Ouates, Switzerland) was used for TBS measurement. “TBS worse than BMD” discordance was defined as partially degraded TBS with normal BMD, or degraded TBS with normal BMD, or degraded TBS with osteopenia. The discordance prevalence was determined, and univariable and multivariable logistic regression analyses were performed to identify the factors associated with the discordance. Our study involved 363 participants with T2DM, of whom 125 (34.44%) were men and 238 (65.56%) were women. The mean age (± SD) was 63.83 (± 7.35) years. The “TBS worse than BMD” discordance was observed in 65 (17.91%, 95% CI 14.28, 22.21) subjects. The discordance was significantly more prevalent in women (21.01%) compared to men (12.00%). After adjusting for other variables, waist circumference emerged as the only significant determinant for the discordance ( P < 0.001). Every 1 cm increase in waist circumference increased the odds of discordance by 13% (OR: 1.13, 95% CI 1.07, 1.19). The “TBS worse than BMD” discordance was present in approximately one out of every five to six older adults with T2DM. Waist circumference emerged as the only significant determinant after adjustment, indicating the potential contribution of central adiposity to this discordance. However, the use of TBS iNsight software (version 2.2) may mean that tissue thickness was not appropriately accounted for in our study. Our findings provide evidence in support of incorporating TBS alongside BMD in fracture risk assessment, particularly among older individuals with T2DM and elevated waist circumference.