We assessed the relationship between insulin resistance, serum insulin-like growth factor 1 (IGF-1) levels, and common carotid intima-media thickness (CC-IMT) in morbidly obese young patients. A total of 249 patients (aged 37.9 ± 9.8 years, body mass index [BMI] 45.6 ± 8.3 kg/m2) were evaluated (metabolic tests, serum IGF-1 measurements, homeostasis model assessment—insulin resistance [HOMA-IR], and ultrasonographically assessed CC-IMT) in a research program for bariatric surgery candidates. After adjusting for age, gender, BMI, systolic blood pressure, uric acid, antihypertensive and lipid-lowering treatment, metabolic syndrome, and metabolic class, both HOMA-IR and IGF-1 z-score were significantly associated with CC-IMT. These results were confirmed in logistic regression analysis, in which age (β = 1.11, P = .001), gender (β = 3.19, P = .001), HOMA-IR (β = 1.221, P = .005), and IGF-1 z-score (β = 1.734, P = .009) were the only independent determinants of abnormal CC-IMT, presumably modulating the effect of the other risk factors included in the regression. Area under the receiver-operating characteristic curve for the model was 0.841 (confidence interval: 0.776-0.907; P < .001). In conclusion, in morbidly obese young adults, insulin resistance and IGF-1 z-score are significantly associated with CC-IMT, independent of other major cardiovascular risk factors.