| 1 Background and ObjectiveType 2 diabetes mellitus(T2DM)and osteoporosis(OP)are the common endocrine and metabolic diseases,incidence of them has been increasing in recent years,and more and more attention has been paid to the harm of them to the body.Diabetes is one of the important causes of secondary osteoporosis.With the increase of the incidence of patients with T2DM,the prevalence of T2DM secondary osteoporosis is also showing a rising trend year by year.In turn,as an important complication of the skeletal system of T2DM,osteoporosis will further aggravate the difficulty of blood glucose management.At present,the specific pathological mechanism of osteoporosis secondary to diabetes is not clear,but more and more studies suggest that oxidative stress,chronic inflammation,insulin resistance and so on may be the common mechanisms of T2DM and OP.Cystatin C(Cys C),a cysteine protease inhibitor,is a low molecular weight protein in human cells and fluids,which can early and sensitively reflect glomerular filtration damage in diabetic nephropathy.It has been proved to be involved in the body’s chronic inflammatory response,coagulation process,etc,through thses mechanism,Cys C may affect bone remodeling and intervene in the occurrence and development of OP.Serum uric acid(SUA),the end products of purine metabolism in vivo,has been shown to have antioxidant stress in previous studies.As an endogenous antioxidant,it may play a beneficial role in bone metabolism during the pathological process of OP.Previous studies suggested that serum Cys C and SUA might be related to OP.Therefore,this study was to analyze the relationship between serum Cys C,SUA and bone mineral density(BMD)in patients with T2DM,and to explore the effect of serum Cys C and SUA on osteoporosis in patients with T2DM.2 Materials and methodsAs a retrospective study,a total of 213 patients with T2DM were enrolled,treated in the Department of Endocrinology of the Second Affiliated Hospital of Zhengzhou University from May 2018 to December 2019.Their clinical history and blood biochemical examination results were collected.All used dual-energy X-ray absorptiometry(DXA)method to determine the bone mineral density of lumbar L1-L4 and bilateral proximal femur.Based on the results of bone mineral density measurement and/or brittle fracture,the participants were divided into two groups:non-osteoporosis group and osteoporosis group,of which 117 were in the non-osteoporosis group(52 males and 65 females),96 patients were in the osteoporosis group(14 males and 82 females).The differences of clinical and biochemical indexes and BMD between the groups were compared by t test/chi square test/non-parametric test.Then the correlation between Cys C,SUA and BMD,correlation between Cys C,SUA and other indicators were analyzed by Pearson/Spearman correlation analysis.The influence of Cys C,SUA and other factors on osteoporosis in patients with T2DM was analyzed with logistic regression.The prediction value of Cys C on osteoporosis in T2DM was analyzed by ROC curve.All data were analyzed by SPSS 21.0,P<0.05 statistically significant.3 Results3.1 Compared with the non-osteoporosis group,the age,HDL-C and Cys C of the osteoporosis group were significantly higher,BMI,2hPG,ALB,SUA and BMD of all parts were significantly lower(P<0.05).The proportion of osteoporosis in female patients with T2DM was significantly higher than that in male patients among selected patients(P<0.05).There was no significant difference in course of disease,SBP,FPG,HbAlc,INS,C peptide,TC,TG,LDL-C,CA,P,alt,AST,ALP,TP,Mao,bun,CRE between the two groups(P>0.05).3.2 Correlation analysis showed that L1-L4BMD positively correlated with BMI,SUA(r=0.192,0.284,P<0.05),negatively correlated with age,gender(female),HDL-C,Cys C(r=-0.140,-0.413,-0.159,-0.234,P<0.05);BMD of left femur positively correlated with BMI,DBP,SUA(r=0.230,0.233,0.223,P<0.05),negatively correlated with age,gender(female),course of disease,Cys C(r=-0.406,-0.273,-0.184,-0.418,P<0.05);BMD of right femur positively correlated with BMI,DBP,FPG,SUA(r=0.240,0.229,0.140,0.238,P<0.05),negatively correlated with age,gender(female),Cys C(r=-0.393,-0.297,-0.388,P<0.05).3.3 The correlation analysis of Cys C,SUA and other clinical indexes showed that Cys C was positively correlated with age and course of disease(r=0.609,0.317,P<0.05),but not with gender,BMI and HbAlc(P>0.05).And SUA was positively correlated with BMI(r=0.159,P<0.05),negatively correlated with age(r=-0.165,P<0.05),but was no significant correlation with gender,course of disease,HbAlc(P>0.05).3.4 Binary logistic regression analysis showed that the risk of osteoporosis in patients with T2DM was positively correlated with Cys C(OR=95.549,P<0.05),and negatively correlated with SUA(OR=0.992,P<0.05),when did not adjust the related influence factors.After adjustment for factors including age,gender,BMI,the occurrence of osteoporosis was still significantly positively correlated to Cys C(OR=63.049,P<0.05),and significantly negatively correlated to SUA(OR=0.992,P<0.05).3.5 The value of Cys C of osteoporosis for patients with T2DM was analysed by ROC curve.The AUC area of Cys C was 0.772[cut-off value was 1.075,sensitivity was 0.573,specificity was 0.855(95%CI:0.710-0.835)].4 Conclusions4.1 The T2DM patients with high Cys C,low SUA are more likely to have a decrease in BMD,among them,low BMI,elder and female patients are more significant.The higher level of SUA in the normal range may plays a positive role in the maintenance of BMD.4.2 Serum Cys C is an independent risk factor of osteoporosis in patients with T2DM.To a certain,the determination of serum Cys C has a predictive value for the diagnosis of osteoporosis in patients with T2DM. |
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