Metabolic diseases (MetS) are increasing among adults and are linked to cardiovascular disease (CVD) due to atherosclerosis. Previous research suggests that common carotid artery intima-media thickness (CCA IMT) can indicate atherosclerosis and predict CVD risk in adults. This study aims to use CCA IMT as a measure to investigate the association between MetS and subclinical atherosclerosis in young and middle-aged adults. This is a cross-sectional study that enrolled subjects between the ages of 20 and 64 without CVD were enrolled. After a thorough clinical examination and biochemical evaluation, the enrolled subjects underwent ultrasonography of both carotid arteries to measure CCA IMT. The presence and number of MetS components were determined using the National Cholesterol Education Program ATP III definition. Multiple linear regression models were used to assess the association between MetS, cardiovascular risk factors, and CCA IMT. Our study shows that MetS and its components are significantly associated with CCA IMT in young and middle-aged adults. Furthermore, the presence of risk factors for MetS increases the risk of subclinical atherosclerosis, which progressively increases with each additional component. [ABSTRACT FROM AUTHOR]