Beyond glycemia: renal resistive index provides robust discrimination and incremental clinical utility for proteinuria in type 2 diabetes

Abstract Background Diabetic kidney disease (DKD) is a major complication of type 2 diabetes mellitus (T2DM), with proteinuria being a primary clinical marker. This study explores the renal resistive index (RA_RI), measured by Doppler ultrasound, as a non-invasive vascular biomarker for detecting and classifying proteinuria severity in T2DM patients. Methods A cross-sectional study was conducted on 100 patients with T2DM, equally divided into proteinuric and non-proteinuric groups. Clinical, biochemical, and Doppler ultrasonographic data were analyzed. Diagnostic performance of RA_RI was assessed using ROC analysis, regression models, and decision-curve analysis. Results RA_RI was significantly higher in proteinuric individuals (0.65 ± 0.03) compared to non-proteinuric individuals (0.58 ± 0.01, p <0.001). At a cut-off of 0.605, RA_RI achieved 92% sensitivity and 100% specificity. RA_RI remained an independent predictor after adjustment. A positive correlation ( ρ = 0.40, p = 0.0037) was found between RA_RI and mildly increased albuminuria, indicating early vascular involvement. Conclusion RA_RI is a promising adjunct for early and non-invasive identification of proteinuria and albuminuria progression in T2DM. Its integration may enhance DKD risk stratification when used alongside traditional markers.