Comparison of GFR estimation in patients with diabetes mellitus using the EKFC and CKD-EPI equations.

Background: The estimation of glomerular filtration rate (eGFR) is essential in the early detection of diabetic nephropathy. We herein compare the performance of common eGFR formulas against a gold standard measurement of GFR in patients with diabetes mellitus.

Methods: GFR was measured in 93 patients with diabetes mellitus using iohexol clearance as the reference standard. The performance of the creatinine- and cystatin C-based EKFC formulas (2021, 2023) and the CKD-EPI formulas (2009, 2012) was compared against measured GFR.

Results: Sixty patients with type 2 diabetes mellitus and 33 patients with type 1 diabetes mellitus were included. The creatinine-based EKFC formula showed lower bias and higher accuracy than the CKD-EPI formula. No significant difference was observed between the cystatin C-based formulas. The combined creatinine- and cystatin C-based formulas had the highest accuracy and lowest bias. Body fat or diabetes type did not significantly influence the accuracy of the cystatin C-based formulas.

Conclusions: Our study demonstrated a slight advantage of the creatinine-based EKFC formula over the CKD-EPI formula in patients with diabetes. However, both for the CKD-EPI and the EKFC formula, the best performance was achieved by the combined creatinine- and cystatin C-based formulas.