Background: Endothelial dysfunction serves as an early indicator of atherosclerosis, preceding structural changes. Its assessment offers insight into the preclinical phase of cardiovascular disease, particularly crucial in Type 2 Diabetes Mellitus (T2DM) due to its association with glycemic control and disease duration. Flow-mediated dilation (FMD), reliant on endothelial nitric oxide release in response to shear stress, reliably gauges endothelial function across various conditions. Aim of the Study: This study aimed to evaluate endothelial dysfunction in T2DM patients compared to age- and sex-matched healthy controls. Additionally, it sought to correlate the duration of diabetes with the prevalence of endothelial dysfunction and examine its association with atherosclerosis risk factors in T2DM. Methodology: Non-invasive assessment using high-resolution Duplex Doppler Ultrasound of the Brachial Artery was conducted on 50 T2DM cases with or without vascular complications and 20 healthy controls. FMD, calculated as percentage increase in brachial artery diameter with increased flow, was employed to quantify endothelial function. Results: Endothelial dysfunction was observed in 20% of diabetics but absent in controls. Mean FMD values were significantly lower in diabetics (8.38 ± 12.32%) compared to controls (17.12 ± 10.53%; p < 0.007). FMD decline was noted across diabetes durations (10 years: 3.50 ± 1.61%), though prevalence did not escalate with longer duration. Conclusion: T2DM patients exhibit significantly impaired endothelial function compared to healthy counterparts, as evidenced by reduced FMD. The prevalence of endothelial dysfunction did not correlate with diabetes duration but was associated with hypertension, family history of diabetes, and smoking. Early intervention targeting these risk factors and optimizing glycemic control may mitigate vascular complications in T2DM.