Cystatin C measurement leads to lower metformin dosage in elderly type 2 diabetic patients

摘要

The aim of this study was to provide evidence for the hypothesis that estimated glomerular filtration rate from serum Cystatin C ( cys) is better to be determined for all elderly type 2 diabetes mellitus (T2 ) patients based on cys upward and downward reclassification rate for hypothetical metformin dose reduction by cys at the decision point of 45  /min/1.73 m . A total of 265 consecutive T2 elderly patients (age range 65‐91 years) from outpatient diabetic clinic were included in the study. The Kidney Disease Improving Global Outcomes ( ) guidelines for metformin dosing were strictly followed. Estimated glomerular filtration rate from serum creatinine ( crea) led to results of metformin eligibility. Each of the results of crea‐based eligibility was further compared to cys‐based eligibility. Creatinine was measured by enzymatic method standardized against international reference material 967. Cystatin C was determined by method traceable to 471 international standard. crea and cys were calculated according to Chronic Kidney Disease Epidemiology Collaboration ( ‐ ) equations. A downward reclassification rate was higher than upward reclassification rate (31 vs 3, respectively;  IQR) crea was higher than cys (73 (58‐85) vs 63 (50‐75) /min/1.73 m , respectively;  eGFRcys reclassified significant proportion of patients with T2 from metformin eligible stages to less or non‐eligible stages. The downward reclassification was more frequent in patients older than 80 years (  eGFR selects more complicated patients, where lower doses of metformin are possibly advisable. We recommend calculating both crea and cys for metformin dosing in elderly patients with T2DM.