Previous evidence associates insulin resistance with arterial stiffness in various pathologies, yet limited reports exist in healthy adults. Therefore, this study aims to estimate the association between insulin resistance and arterial stiffness in healthy adults. The cross-sectional EVasCu study enrolled 390 participants (42.05 ± 13.15 years). ANCOVAs, unadjusted (model 1) and adjusted (model 2), explored the association between arterial stiffness markers (aortic Pulse Wave Velocity [aPWV], Augmentation Index [AIx@75] and Cardio-Ankle Vascular Index [CAVI]), and insulin resistance markers (Homeostasis Model Assessment of Insulin Resistance [HOMA-IR], Quantitative Insulin Sensitivity Check Index [QUICKI] and Triglycerides-Glucose [TyG]). In model 1, all insulin resistance markers were associated with aPWV, HOMA-IR and QUICKI were associated with AIx@75, and the TyG index was associated with CAVI. In model 2, HOMA-IR and QUICKI increased aPWV by 0.179 and 0.156 m/s (p = 0.001 and p = 0.011), and AIx@75 by 4.17 and 5.39% (p = 0.009 and p = 0.003). The EVasCu study offers valuable insights into the relationship between insulin resistance and arterial stiffness in healthy adults, providing a deeper understanding of metabolic and cardiovascular health. By examining this influence, we embark on an intriguing exploration of how these factors interplay in the human body.