Study of Cystatin C and Renal Resistive Index in Type 2 Diabetes Mellitus Patients to Detect Early Diabetic Kidney Disease.

Background: Diabetic kidney disease (DKD) is a major cause of chronic kidney disease and end-stage renal failure among individuals with type 2 diabetes mellitus (T2DM). Traditional markers such as serum creatinine and albuminuria have limited sensitivity in early disease stages. Cystatin C and renal resistive index (RRI) are emerging as sensitive early indicators.

Objectives: The study aimed to assess the diagnostic utility of serum cystatin C and RRI in the early detection of renal dysfunction in T2DM patients and to evaluate their correlation with estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (UACR).

Materials and methods: A cross-sectional study involving 100 patients with T2DM was conducted. Serum cystatin C, serum creatinine, urine albumin, and eGFR (using Chronic Kidney Disease Epidemiology Collaboration creatinine-cystatin equation) were measured. Doppler ultrasonography was used to determine RRI. Pearson's correlation and multiple regression analyses were performed.

Results: Elevated cystatin C levels were seen in 91% of subjects, whereas only 63% had abnormal serum creatinine. RRI was raised in 62% of patients. eGFR correlated negatively with UACR (r = -0.998), serum creatinine (r = -0.881), RRI (r = -0.712), and cystatin C (r = -0.552). UACR and RRI were significant predictors of eGFR in multivariate analysis (P < 0.001 and P = 0.030, respectively).

Conclusion: Cystatin C and RRI provide early insights into renal dysfunction in T2DM and should be integrated with existing diagnostic parameters for improved DKD screening.