Abstract: Objective　To investigate the suitable equation of glomerular filtration rate（GFR） in estimating renal function for type 2 diabetes mellitus patients，and to compare the application effects of modification of diet in renal disease（MDRD）, reexpressed modification of diet in renal disease（rMDRD）, chronic kidney disease epidemiology collaboration（CKD-EPI） and cystatin C（Cys C）-based equations for GFR.  Methods　Clinical data from 178 type 2 diabetes mellitus patients were collected for the detection of serum creatinine（SCr） level，Cys C level and renal clearance of ^99mTc-diethylenetriamine pentaacetic acid-deoxyglucose（^99mTc-DTPA） which was used as the reference of isotopic GFR（iGFR）. According to the standard of the American Diabetes Association（ADA）, the 178 patients were classified into 3 groups [GFR：15-59, 60-89 and ≥90 mL/（min·1.73 m²）]. The equations for estimated GFR（eGFR） were compared with iGFR by paired t test，linear analysis，Bland and Altman procedures，receiver operating characteristic （ROC） curves and 15%，30% and 50% coincidences.  Results　When GFR<60 mL/（min·1.73 m²）， there was no significant difference between eGFR and iGFR in MDRD equation，but when GFR≥60mL/（min·1.73 m²），there was significant difference（P＜0.001）. There was no significant difference of eGFR for rMDRD equation in accuracy and diagnostic sensitivity. When GFR≥90 mL/（min·1.73 m²），the coincidences were higher in CKD-EPI equation than those in MDRD and rMDRD equation，but when GFR 60-89 mL/（min·1.73 m²），they were lower than those in Cys C GFR equation. The Cys C GFR equation had a better correlation with eGFR and iGFR，a less bias，a higher deviation and a higher coincidence than those in MDRD and rMDRD equations，especially when GFR≥90 mL/（min·1.73 m²）， only there was no significant difference between eGFR and iGFR, and Cys C GPR equation was better than the other 3 equations.  Conclusions　The 4 equations can estimate GFR accurately for type 2 diabetes mellitus patients when GFR<60 mL/（min·1.73 m²），but when GFR≥90 mL/（min·1.73 m²），Cys C GFR equation shows a significant superiority than the old SCr based equations.

Key words: Glomerular filtration rate, Estimating equation, Type 2 diabetes mellitus, Cystatin C