Abstract

Background: In patients with type 2 diabetes mellitus, reduced glomerular filtration rate may progress silently and does not always coincide with elevated albuminuria. The aim of this study was to evaluate the discriminative value of serum cystatin C and urine albumin-to-creatinine ratio (uACR) for identifying reduced glomerular filtration rate (eGFR <60 mL/min/1.73 m²) in patients with type 2 diabetes mellitus.

Methods: A cross-sectional descriptive study was conducted on 132 patients with type 2 diabetes mellitus attending the Hospital for Rehabilitation and Occupational Diseases in Ho Chi Minh City. Serum cystatin C and uACR were measured and compared against eGFR calculated using the CKD-EPI creatinine equation.

Results: Mean eGFR was 75.5 ± 18.5 mL/min/1.73 m²; 19.7% of patients had eGFR <60 mL/min/1.73 m². Mean serum cystatin C was 1.14 ± 0.39 mg/L; median uACR was 14.9 (8.7-44.1) mg/g. ROC analysis demonstrated that cystatin C had good discriminative value for identifying reduced eGFR, with an AUC of 0.866 (95% CI: 0.798-0.934; p <0.001), an optimal cutoff of 1.11 mg/L yielding a sensitivity of 92.3% and a specificity of 67.9%. uACR showed limited discriminative performance (AUC = 0.583; p = 0.210). The combined model incorporating both cystatin C and uACR yielded an AUC of 0.872 (95% CI: 0.806-0.938; p <0.001).

Conclusion: Serum cystatin C demonstrated good discriminative value for identifying reduced glomerular filtration rate in patients with type 2 diabetes mellitus, whereas uACR alone showed limited performance. Incorporating serum cystatin C into kidney function assessment may help identify reduced GFR at the time of evaluation in this patient population.