Effect of BMI-Discordant Abdominal Tissue Thickness on Fracture Probability: A Registry-Based Study

Bone microstructure and TBS in diabetes: what have we learned? A narrative review

Diabetes is associated with an increased risk of fracture. Areal bone mineral density (aBMD), the most reliable indicator of fracture risk in healthy adults, is low in patients with type 1 diabetes mellitus but normal or high in patients with type 2 diabetes mellitus. Most trabecular and cortical parameters measured by high-resolution peripheral quantitative computed tomography (HR-pQCT) are lower in type 1 diabetes and higher in type 2 diabetes, in parallel with aBMD. In contrast, lumbar spine trabecular bone score (TBS) has been reported to be lower in women with both type 1 and type 2 diabetes. The discordance between improved bone microstructure and degraded TBS reflects the effect of central obesity (currently the subject of a revision to the TBS algorithm). Meanwhile, evidence supports use of TBS in conjunction with aBMD and/or FRAX for improved fracture prediction in patients with type T2D. This position paper, on behalf of the Bone and Diabetes Working Group of the International Osteoporosis Foundation, summarizes alterations in bone microarchitecture measured by HR-pQCT in diabetes. It also addresses the technical and clinical considerations of the trabecular bone score, particularly discussing the significance of this measurement in individuals with diabetes and the influence of abdominal fat.

Fracture Risk Assessment in Metabolic Syndrome in Terms of Secondary Osteoporosis Potential. A Narrative Review

Osteoporosis is a major global public health problem with the associated bone fractures contributing significantly to both morbidity and mortality. In many countries, osteoporotic fractures will affect one in three women and one in five men over the age of 50. Similarly, diabetes, obesity, and metabolic syndrome (MetS) are among the leading public health problems due to their worldwide prevalence and burden on health budgets. Although seemingly disparate, metabolic disorders are known to affect bone health, and the interaction between fat and bone tissue is increasingly well understood. For example, it is now well established that diabetes mellitus (both type 1 and 2) is associated with fracture risk. In this narrative review, we focus on the potential link between MetS and bone health as expressed by bone mineral density and fracture risk. This narrative review demonstrates the association of MetS and its components with increased fracture risk, and also highlights the need for fracture risk assessment in patients with obesity and MetS.

Metabolic factors are not the direct mediators of the association between type 2 diabetes and osteoporosis

Objective

The causal relationship between type 2 diabetes mellitus (T2DM) and osteoporosis (OS) remains unclear. This study aims to investigate the causal relationship and explore the potential metabolic mechanism and its mediating role.

Methods

We conducted a comprehensive study, gathering data on 490,089 T2DM patients from the genome-wide association study (GWAS) database and selecting OS data from FinnGen and MRC-IEU sources, including 212,778 and 463,010 patients, respectively, for causal analysis. Simultaneously, we explored the potential roles of three obesity traits and 30 metabolic and inflammation-related mediating variables in the causal relationship.

Results

There is a strong causal relationship between T2DM and OS. The data from our two different database sources appeared in the same direction, but after correcting for body mass index (BMI), waist circumference (WC), and waist-to-hip ratio (WHR), the direction became the same. T2DM may increase the risk of OS [odds ratio (OR) > 1.5, p < 0.001]. Steiger's test results show that there is no reverse causality. No risk factors related to glycolipid metabolism, amino acid metabolism, and inflammation were found to mediate the causal relationship.

Conclusion

This study's findings indicate a robust causal relationship between T2DM and OS, influenced by relevant factors such as BMI. Our results shed light on the pathogenesis of OS and underscore the importance for clinicians to treat metabolic disorders to prevent osteoporosis.

Clinical Use of Trabecular Bone Score: The 2023 ISCD Official Positions

Osteoporosis can currently be diagnosed by applying the WHO classification to bone mineral density (BMD) assessed by dual-energy x-ray absorptiometry (DXA). However, skeletal factors other than BMD contribute to bone strength and fracture risk. Lumbar spine TBS, a grey-level texture measure which is derived from DXA images has been extensively studied, enhances fracture prediction independent of BMD and can be used to adjust fracture probability from FRAX® to improve risk stratification. The purpose of this International Society for Clinical Densitometry task force was to review the existing evidence and develop recommendations to assist clinicians regarding when and how to perform, report and utilize TBS. Our review concluded that TBS is most likely to alter clinical management in patients aged ≥ 40 years who are close to the pharmacologic intervention threshold by FRAX. The TBS value from L1-L4 vertebral levels, without vertebral exclusions, should be used to calculate adjusted FRAX probabilities. L1-L4 vertebral levels can be used in the presence of degenerative changes and lumbar compression fractures. It is recommended not to report TBS if extreme structural or pathological artifacts are present. Monitoring and reporting TBS change is unlikely to be helpful with the current version of the TBS algorithm. The next version of TBS software will include an adjustment based upon directly measured tissue thickness. This is expected to improve performance and address some of the technical factors that affect the current algorithm which may require modifications to these Official Positions as experience is acquired with this new algorithm.