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- and serum cystatin C -based eGFR (eGFRcr, eGFRcys) in individuals with type 1 diabetes (T1D) at different stages of albuminuria, and to identify the factors associated with the discordance, and to study the association of SCysC, eGFRcr, and eGFRcys with incident moderate albuminuria.

Research Design and Methods We included 3,769 FinnDiane Study participants (51.8% men) with T1D without kidney failure and data on SCr and SCysC available. Median age was 36.6 (interquartile range 27.7-46.4) years and median duration of diabetes 19.5 (10.9-29.2) years. eGFRcys and eGFRcr were calculated using the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equations. We assessed the rate of concordance and discordance in the groups -15≤eGFRdiff<15, eGFRdiff<-15 (negative) and eGFRdiff ≥15 (positive) ml/min/1.73 m2, where eGFRdiff=eGFRcys-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 absolute eGFRdiff was 14.0±12.2 ml/min/1.73 m2. The overall concordance rate was 62.9%, the negative discordance rate 20.4% and the positive discordance rate 16.7%. Sex, albuminuria status, smoking, retinal laser photocoagulation, HbA1c, HDL-C, hs-C-reactive protein and insulin dose per kg contributed to the discordance. Both SCysC and eGFRcys were associated with the incidence of moderate albuminuria, while eGFRcr was not. Discordant eGFRcys and eGFRcr were common in individuals with T1D.

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