Clinical Factors Associated With Trabecular Bone Score In Postmenopausal Women With Type 2 Diabetes Mellitus

Objective:Patients with type 2 diabetes mellitus(T2DM)have an increased risk of fracture but normal or even higher bone mineral density(BMD)than those without T2DM.Since BMD cannot fully account for the fracture risk of T2DM,the assessment of bone quality is of concern.Trabecular bone score(TBS)is a new index that reflect bone quality through changes in bone microarchitecture.The aim of the study is to investigate the alterations in bone quality by measuring TBS and to figure out significant clinical factors associated with TBS in postmenopausal women with T2DM.Methods:A total of 263 patients were enrolled from January 2017 to August 2018.Demographic data of each patient were collected in detail.Height and weight were measured and body mass index(BMI)was calculated.Blood tests including FPG,HbA1c,FCP,TC,TG,HDL-C,LDL-C,CTx,OC,TP1NP,total VD,etc.FPG and FCP were input into HOMA2 calculator to get HOMA-IR and HOMA-β.All patients underwent DXA to measure the bone mineral density of lumbar spine(LS-BMD),femoral neck and total hip.BMD/BMI was calculated by LS-BMD/BMI.The lumbar DXA image was uploaded to the TBS iNsight software to obtain the TBS value.The diagnosis of degraded bone microarchitecture was based on the standards recommended by international TBS group in 2012:TBS≥1.350 is normal;1.200<TBS<1.350 is partially degraded;TBS≤1.200 is degraded.Detection rates among three groups was analyzed by Chi-square test.One-way ANOVA was applied to compare the difference of every variable among three groups,and t-test was used for comparison between the two groups.Pearson correlation and multiple linear regression were used for correlation and regression analysis.P<0.05 was considered statistically significant.Results:1.In 263 postmenopausal women with T2DM,31.9%had degraded bone microarchitecture,55.5%had partially degraded bone microarchitecture.All the patients was grouped by bone mineral density into normal bone mass(n=54),decreased bone mass(n=138)and osteoporosis(n=71).Even if the bone mass measured by DXA is normal,53.7%(n=29)of the patients have partially degraded bone microarchitecture,14.8%(n=8)of the patients have degraded bone microarchitecture.The detection rates of degraded bone microarchitecture,partially degraded bone microarchitecture,impaired bone microarchitecture(partially degraded+degraded)were different among three groups with statistical significance(P<0.001).2.Of all patients,age(66.54±7.33)year,BMI(24.48±3.39)kg/m~2,TBS(1.24±0.103),were divided into three groups:normal bone microarchitecture(n=33),partially degraded bone microarchitecture(n=146),degraded bone microarchitecture(n=84),analysis of variance showed LS-BMD(1.19±0.231 vs 1±0.131 vs 0.962±0.111,P=0.001),BMD/BMI(0.054±0.015 vs 0.041±0.006 vs 0.039±0.007,P<0.001)among three groups reached statistical significance.Compared with normal bone microarchitecture group,impaired bone microarchitecture group(n=230)had higher FPG(9.485±3.614 vs 6.291±1.813,P=0.001),HbA1c(9.432±2.578 vs 7.438±1.622,P=0.011),and lower LS-BMD(0.986±0.125 vs 1.19±0.231,P=0.042),BMD/BMI(0.0404±0.0065 vs 0.0543±0.0149,P=0.034)and OC(13.11±5.12 vs 18.75±8.79,P=0.028).3.Pearson correlation analysis showed that TBS had negative correlation with age(r=-0.284,P=0.024),BMI(r=-0.266,P=0.035),TG(r=-0.226,P=0.045),and positive correlation with LS-BMD(r=0.342,P=0.006),BMD/BMI(r=0.424,P=0.001),respectively.There was no significant correlation between TBS and FPG,HbA1c,FCP,HOMA-IR,HOMA-β,TC,HDL-C,LDL-C,CTx,OC,TP1NP,total VD(P>0.05).4.Stepwise regression analysis was performed with TBS as the dependent variable and age,BMD/BMI,FPG,HbA1c,TG and OC as independent variables,regression equation 1:TBS=1.505-0.006×age+3.951×BMD/BMI(P<0.001),adjusted R~2=0.310,age had a greater impact on TBS than BMD/BMI.Stepwise regression analysis was performed again with age,LS-BMD,BMI,FPG,HbA1c,TG and OC as independent variables,regression equation 2:TBS=1.544-0.007×age-0.036×TG+0.224×LS-BMD(P<0.001),adjusted R~2=0.356,and the impact of age,LS-BMD and TG on TBS decreased successively.Conclusion:In postmenopausal women with T2DM,even if bone mineral density measured by DXA was normal,there was still a large proportion of patients with degraded or partially degraded bone microarchitecture;Poor blood glucose control and low OC were associated with decreased TBS;TBS had positive correlation with LS-BMD,BMD/BMI,while negative correlation with age,TG and BMI;TBS in postmenopausal women with T2DM could be estimated by age and BMD/BMI,combining age,TG and LS-BMD together estimated TBS better.