Background: Diabetic nephropathy represents a prevalent manifestation of chronic kidney disease (CKD) and stands as the most common microvascular complication observed among individuals with diabetes. Objectives: This study aimed to investigate Doppler ultrasonographic parameters of the renal arteries in diabetic patients and to examine their correlation with renal function markers such as serum creatinine, estimated Glomerular filtration rate (eGFR), and proteinuria. Patients and methods: A total of 300 adult diabetic patients were enrolled in this observational, cross-sectional study. Based on the progression of diabetic kidney disease, participants were stratified into three groups: Group I (preclinical stage) involved 56 individuals showing no clinical or biochemical signs of renal impairment, group II consisted of 88 patients with established diabetic nephropathy and group III that comprised 156 patients in the end-stage of diabetic renal disease. Results: Group 3 patients exhibited a markedly higher left RI relative to groups 1 and 2 (p < 0.001). The left RI correlated positively and strongly with albuminuria (r = 0.60), urea (r = 0.50) and creatinine (r = 0.65), and HbA1c (r = 0.45) with high statistical significance (p < 0.001). A robust inverse correlation was observed between left RI and eGFR (r = –0.68, p < 0.001). Conclusion:The renal resistive index (RRI) exhibited strong correlations with key biochemical markers, including albuminuria, creatinine, and HbA1c, while inversely correlated with eGFR across different stages of diabetic renal disease, which highlights the value of Doppler ultrasound as a non-invasive tool for early detection and monitoring of disease progression.