Bone quality in Chinese postmenopausal women with type 2 diabetes mellitus: a cross-sectional study

Abstract

Introduction: Type 2 diabetes mellitus (T2DM) is associated with 1.34-fold increase in hip fracture risk despite higher bone mineral density (BMD). Trabecular bone score (TBS), an indirect index of bone microarchitecture based on lumbar spine image on dual-energy X-ray absorptiometry, captures a larger portion of T2DM-related fracture risk. Here we compared the bone quality in Chinese postmenopausal women with T2DM with those without diabetes mellitus (non-DM). Methods: We conducted a cross-sectional study of postmenopausal women, with T2DM patients recruited from the Hong Kong West Diabetes Registry and non-DM patients from the Hong Kong Cardiovascular Risk Factor Prevalence Study, between November 2016 and October 2018. Type 2 diabetes was defined by fasting glucose ≥7.0 mmol/L, 2-hour oral glucose tolerance test (OGTT) ≥11.0 mmol/L, or glycated haemoglobin (HbA1c) ≥6.5%; pre-diabetes (pre-DM) by fasting glucose 5.6-6.9 mmol/L, 2-hour OGTT 7.8-11.0 mmol/L, or HbA1c 5.7% to 6.4%; and euglycaemia by normal fasting glucose, 2-hour OGTT, and HbA1c. Bone mineral density, vertebral fracture assessment, and TBS were measured by dual energy X-ray absorptiometry. Results: A total of 322 patients (104 with T2DM, 218 non-DM) were included. Compared with non-DM patients, those with T2DM were older (63.7 vs 62.1 years, P=0.012) and heavier (25.6 vs 23.2 kg/m2 , P=0.002), and had higher lumbar spine BMD (0.93 vs 0.85 g/cm2 , P<0.001) but lower TBS (1.28 vs 1.26, P=0.031). Vertebral fractures were more prevalent in patients with T2DM and pre-DM compared with those with euglycaemia (P=0.03). Multivariable linear regression analysis revealed that TBS was significantly lower in patients with T2DM compared with non-DM patients, after adjustment for age, body mass index, and lumbar spine BMD (P<0.001). Trabecular bone score showed a significant decreasing trend with worsening glycaemic status after adjusting for covariates (1.30, 1.27 and 1.26 in patients with euglycaemia, pre-DM and T2DM, respectively, P=0.001). Subgroup analysis revealed that among patients aged ≥60 years, TBS was significantly lower in patients with preDM than in those with euglycaemia (P=0.020), but similar to that in patients with T2DM (P=0.206). Conclusion: In Chinese postmenopausal women, T2DM is associated with higher BMD, but lower TBS compared with non-DM. Trabecular bone score decreases with worsening glycaemic status. Lower TBS with more vertebral fractures can be observed starting from pre-DM in older age-group, suggesting potential impact of early intervention of pre-DM from the perspective of bone health, which warrants further studies.