Comparison of Serum Creatinine- and Cystatin C-Based eGFR at Baseline and Their Prediction of Incident Moderate Albuminuria in Individuals With Type 1 Diabetes.

OBJECTIVE

To assess the concordance between serum creatinine (SCr)- and serum cystatin C (SCysC)-based estimated glomerular filtration rate (eGFR) in individuals with type 1 diabetes (T1D) at different stages of albuminuria; identify the factors associated with the discordance; and study the association of SCysC, eGFR of creatinine (eGFRcr), and eGFR of cystatin C (eGFRcys) with incident moderate albuminuria.

RESEARCH DESIGN AND METHODS

We included 3,769 FinnDiane Study participants (51.8% men) with T1D but not kidney failure and with available data on SCr and SCysC. Median age was 36.6 (interquartile range [IQR] = 27.7-46.4) years, and median duration of diabetes was 19.5 (IQR = 10.9-29.2) years. eGFRcys and eGFRcr were calculated using the Chronic Kidney Disease Epidemiology Collaboration equations. We assessed the rate of concordance and discordance in the following three groups: -15 ≤ eGFRdiff < 15, eGFRdiff < -15, and eGFRdiff ≥ 15 mL/min/1.73 m2 (where eGFRdiff = eGFRcys minus eGFRcr), as well as the variables that contributed to the discordance. In addition, the association of CysC, eGFRcr, and eGFRcys with the incidence of moderate albuminuria was evaluated.

RESULTS

The mean (±SD) absolute eGFRdiff was 14.0 ± 12.2 mL/min/1.73 m2. The overall concordance rate was 62.9%, the negative discordance rate was 20.4%, and the positive discordance rate was 16.7%. Sex, albuminuria status, smoking, retinal laser photocoagulation, HbA1c, HDL cholesterol, high-sensitivity C-reactive protein, and insulin dose per kilogram contributed to the discordance. Both SCysC and eGFRcys were associated with the incidence of moderate albuminuria, whereas eGFRcr was not. Discordant eGFRcys and eGFRcr values were common in individuals with T1D.

CONCLUSIONS

These findings suggest SCysC may facilitate early identification of individuals at risk for albuminuria.