Background: Metabolic syndrome (MetS), increasingly diagnosed among the Polish population, is a combination of factors that are associated with an increased risk of atherosclerosis and cardiovascular diseases. Intima-media thickness (IMT) of the common carotid artery has been suggested as, simply, a non-invasive and reproducible marker of the early stages of the atherosclerotic process. The carotid IMT can also be a strong predictor of future cerebral and cardiovascular events. The aim of our study was to evaluate atherosclerotic lesions in carotid vessels in patients with MetS depending on the presence of DMt2 and to assess which demographic factors affect the level of IMT. The study involved 335 subjects diagnosed with MetS, including 211 females (65%) and 124 males (37%) aged 37–82. The diagnosis of MetS was made on the basis of the International Diabetes Federation (IDF) criteria. The patients were divided into two subgroups: with DMt2 and without DMt2. The value of IMT depended on gender, education, and smoking status. We noticed that patients with DMt2 had the highest measurement of IMT compared with other groups (1.01 vs. 0.98). Additionally, a statistically significant difference between the subgroup with DMt2 and those without DMt2 was found (1.01 vs. 0.92;p< 0.005). Ultrasound assessment of the carotid IMT should be used more often in the diagnosis and monitoring of high cardiovascular risk and early progression of atherosclerosis, especially in patients with MetS with current DMt2.