Background: This study aimed to evaluate the impact of Diabetes Mellitus (DM) and Ischaemic Heart Disease (IHD) on the Blood Resistivity Index (RI) of renal arteries in hypertensive patients. The goal was to assess how these comorbid conditions influence renal artery resistance and potential renal dysfunction in hypertensive individuals.Material and Methods: This cross-sectional observational study included 120 hypertensive patients aged between 40 to 80 years, categorized into four groups based on the presence or absence of DM and IHD: Group 1 (Control Group): 30 hypertensive patients without DM or IHD. Group 2 (DM Group): 30 hypertensive patients with DM but without IHD. Group 3 (IHD Group): 30 hypertensive patients with IHD but without DM. Group 4 (DM + IHD Group): 30 hypertensive patients with both DM and IHD. Renal artery Doppler ultrasonography was performed to measure the Resistivity Index (RI), and statistical analysis was conducted using ANOVA to compare the differences between groups.Results: The study found that RI values were significantly higher in the DM, IHD, and DM + IHD groups compared to the Control group. The DM + IHD group had the highest average RI (0.76 ± 0.12). The prevalence of renal artery disease (RI > 0.7) was notably higher in the DM + IHD group (70%) compared to the Control group (6.7%). Statistical analysis revealed significant differences in RI between groups, with the most pronounced effects observed in the DM + IHD group (F = 13.75, p < 0.001).Conclusion: This study emphasizes the significant impact of Diabetes Mellitus and Ischaemic Heart Disease on renal artery resistance in hypertensive patients. The combined presence of DM and IHD leads to significantly higher Resistivity Index values, indicating compromised renal function and vascular resistance. Early monitoring and integrated management of these conditions are crucial to prevent renal and cardiovascular complications. Regular screening using renal Doppler ultrasonography can aid in the early detection and prevention of renal dysfunction in hypertensive patients with these comorbidities.