STUDY OF RENAL FUNCTION IN TYPE 2 DIABETIC PATIENTS BY SERUM CYSTATIN C

Abstract

Aims: to investigate serum Cystatin C level, correlation between serum Cystatin C levels with albuminuria, estimate glomerular filtration rate (eGFR), and renal radiography in type 2 diabetic patients. Materials and methods: We studied 77 healthy subjects without prediabetes or diabetes, and 70 type 2 diabetic patients. We excluded patients with thyroid dysfunction and those taking glucocorticoids that affect the serum Cystatin level. The serum Cystatin C level measured in 2 groups. In type 2 diabetic patients, we measured renal radiography, albuminuria, and estimated GFR using CKD.EPI 2012 formular. Descriptive and cross-sectional study. A statistical analyses of the data was performed using SPSS, Excel 2003. Receiver operating characteristics (ROC) analysis, calculated the area under the curve (AUC) for serum Cystatin C. Results: The level of serum Cystatin C in the type 2 diabetic patients was significantly higher than in the control group (1.45±0.97, 0.97±0.23 mg/L, p<0.001, respectively). The level of serum Cystatin C showed stepwise increase with albuminuria level. The serum cystatin C level in the macroalbuminuria group was significantly higher than microalbuminuria group (2,51±1,13; 1,12±0.69 mg//l, p<0.05, respectively). A positively correlation was observed between eGFR according to CKD.EPI equation based on serum Cystatin C and renal radiography (r=0.710, p<0.001). The positively correlation between eGFR according to CKD.EPI equation based on serum Creatinine-Cystatin C and renal radiography r=0.746, p<0.001). The serum Cystatin C level was significantly higher in patients with GFR < 60 ml/min/1.73m2 than those with ≥ 60 ml/min/1.73m2 (p < 0,001). Serum Cystatin C level was significantly reciprocal correlation between eGFR based on cystatin C serum (r=0.830, p<0.001) or renal radiography (r=0,748, p<0,001). The cutoff value for the identification of GFR < 60ml/min/1.73m2 was 1.28mg/l with a sensitivity of 100.0 (95% CI: 85,6-100,0) and specificity of 95.7 (95%CI:85.1-99.3). AUC was 0,992. Conclusions: The serum cystatin C level in type 2 diabetic patients was significantly higher than the control group. The serum level of Cystatin C in type 2 diabetic patients was stepwise increased with albuminuria level. There was a positive correlation between eGFR based on Cystatin C and renal radiography. A reciprocal correlation between serum Cystatin C level and eGFR calculated by CKD.EPI 2012 formular and GFR by renal radiography. Key words: diabetes, glomerular filtration rate, Cystatin C, albuminuria