title: Comparison of cystatin C- and creatinine-based estimation of glomerular filtration rate according to glycaemic status in Type 2 diabetes.
abstract: OBJECTIVE
  The influence of hyperglycaemia on the performance of glomerular filtration rate (GFR) estimating equations remains to be determined. We compared the performance of creatinine-based GFR with cystatin C-based GFR in patients with Type 2 diabetes according to glycaemic status.
  
  
  METHODS
  In a cross-sectional study of 210 patients with Type 2 diabetes, we staged glycaemic status by HbA(1c) tertiles [HbA(1c) ≤ 75 mmol/mol (9.0%) (n = 70), HbA(1c) 76-95 mmol/mol (9.1-10.8%) (n = 70), HbA(1c) >95 mmol/mol (10.8%) (n = 70)] and measured GFR. Isotopic GFR was measured using renal dynamic imaging with (99m) Tc-diethylene-triamine-penta-acetic acid. Estimated GFR (eGFR) was measured using creatinine-based formulae (Cockcroft-Gault-eGFR, the Modification of Diet in Renal Disease equation-eGFR and the Chronic Kidney Disease Epidemiology Collaboration formula-eGFR) and a cystatin C-based formula (cystatin C-eGFR).
  
  
  RESULTS
  The isotopic GFR of all patients was 93.1 ± 34.1 ml min(-1) 1.73 m(-2). All methods for estimating GFR underestimated isotopic GFR [Cockcroft-Gault-eGFR (68.8 ± 38.6 ml min(-1) 1.73 m(-2) ) (P < 0.05), Modification of Diet in Renal Disease-eGFR (74.8 ± 31.3 ml min(-1) 1.73 m(-2) ) (P < 0.05), Chronic Kidney Disease Epidemiology Collaboration-eGFR (72.9 ± 26.6 ml min(-1) 1.73 m(-2)) (P < 0.05) and cystatin C-eGFR (83.5 ± 33.2 ml min(-1) 1.73 m(-2)) (P < 0.05)]. In all patient groups, cystatin C-eGFR was less biased and more accurate than the creatinine-based formulae, especially in the group with HbA(1c) > 95 mmol/mol (10.8%) where there was no difference between cystatin C-eGFR and isotopic GFR.
  
  
  CONCLUSIONS
  Performance of cystatin C-eGFR was superior to creatinine-based GFR in patients with Type 2 diabetes with HbA(1c) >95 mmol/mol (10.8%).
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: S J
authors.initials: SJ
authors.lastname: Oh
authors.forename: J I
authors.initials: JI
authors.lastname: Lee
authors.forename: W C
authors.initials: WC
authors.lastname: Ha
authors.forename: S H
authors.initials: SH
authors.lastname: Jeong
authors.forename: H W
authors.initials: HW
authors.lastname: Yim
authors.forename: H S
authors.initials: HS
authors.lastname: Son
authors.forename: T S
authors.initials: TS
authors.lastname: Sohn
mesh_terms: D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism*; D003404:Creatinine / Q000097:blood*; D003430:Cross-Sectional Studies; D055316:Cystatin C / Q000097:blood*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D003928:Diabetic Nephropathies / Q000097:blood* / Q000503:physiopathology; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D006943:Hyperglycemia / Q000097:blood; D008297:Male; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000503:physiopathology
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D055316:Cystatin C; D003404:Creatinine