The Relationship Of Serum Cystatin C And Homocysteine To Diabetic Nephropathy

Objecyive: To investigate the relationship of serum cystatin C and homocysteine to Type two Diabetic Nephropathy.Methods: Eighty-eight cases of T2DM were choosed as a subject of the study, which was divided into three groups: simple diabetes mellitus(SDM), early diabetes mellitus(EDN) and clinical diabetes mellitus(CDN) according to Mogensen's classification. Twenty healthy volunteers were selected as a control group , the serum level of cystatin C and homocysteine were measured by the methods of immunophrology method and enzyme. At the same time, we collected clinical and laboratory data ,compared the results of normal control group with T2DM groups respectively. We also estimated glomerular filtration rate (GFR) by various formulas and made receiver operating characteristic(ROC) curve to learn the relationship of serum cystatin C and homocystein to glomerular filtration rate.Results:1. The serum level of CysC was increased from control group to the CDN group, in which there were significant differences between these groups (p<0.05, respectively)except for control group vs SDM, The serum level of Hcy was increased from control group to the CDN group, in which there were significant differences between these groups (p<0.05, respectively);2. The serum CysC level was positively correlated with Hcy(r=0.659,P<0.01), disease duration(r=0.557,P<0.01), UAER(r=0.882,P<0.01), Scr(r=0.429,P<0.01) and BUN (r=0.591,P<0.01), the serum Hcy level was positively correlated with disease duration duration(r=0.651,P<0.01), UAER(r=0.711,P<0.01) and Scr (r=0.484, P<0.01), but both the serum CysC level and Hcy level were negatively correlated with GFR .3. Multiple stepwises regression ananysis indicated that serum CysC level was significantely influenced by the UAER and glycated hemoglobin , the Hcy level was significantely influenced by the UAER,disease duration and glycated hemoglobin.4. Areas under the ROC curve indicated that areas under the ROC curve of Ccr,eGFR1,eGFR2,eGFR3,eGFR4 to CysC>1.05mg/L for standard were 0.754,0.781,0.781,0.9793,0.796; the areas under the ROC curve of Ccr,eGFR1,eGFR2,eGFR3,eGFR4 to Hcy>12.5umol/L for standard were 0.734,0.767,0.767,0.768,0.769.so the diagnostic value of CysC>1.05mg/L to glomerular filtration rate was greater than the that of Hcy>12.5umol/L.Conclusion: The study suggests that the injured renal glomerular function,long-term duration of diabetes and the poor control of glucose were the main influencing factors of serum cystatin C and homocysteine levels, especially the increase of microalbuminuria may be looked as a mark of serum cystatin C and homocysteine levels, increase. Serum CysC>1.05mg/L and Hcy>12.5umol/L maybe the critical value to early renal glomerular function damage, to judge glomerular filtration functions the areas under the ROC curve has a good diagnosis value by this bound point, it has better sensitivity and specificity to judge early chronic kidney disease (K-DOQI), and the area under under the ROC curve for boundary point of CysC > 1.05 mg/L is superior. In comparison, the new glomerular filtration rate computation formula developed by compatriots is more suitable for clinical use.