Objective:To explore the value of intima-media thickness quantification technology and Sono CT in evaluating the vascular pathology of carotid artery in patients with type 2 diabetes mellitus. Methods: The carotid artery of 124 patients with type 2 diabetes mellitus and 82 healthy controls were detected respectively. The IMT of the the posterior wall of the carotid artery, and the presence of atherosclerotic plaque were observed. The patients were divided into DM1 group and DM2 group according to with or without hypertention, and the course of disease. Results: In DM1 with hypertention and DM2 without hypertention, the prevalence rates of carotid IMT are 81.5%, rates of carotid plaque are 78.2%, while in control group the data were 40.2% and 31.7%. There was significant difference between the two groups (P < 0. 05). The prevalence rates of carotid plaque of DM2 are higher than DM1, mean carotid IMT of DM2 which detected by QLAB are higher than that of DM1, with highly significant difference.The prevalence rates of carotid IMT and carotid plaque of patients with more than 5 years course of disease are higher than those patients with less than 5 years. Conclusion: The main change of carotid lesions in type 2 diabetes mellitus is the carotid IMT. The second change is carotid plaque. Sono CT technology can improve the resolution capability of the fine structure, increase the visibility of the rim of vascular lesions. The mean IMT measured by QLAB is superior to the maximum IMT in evaluating the vascular pathology of carotid artery in diabetes patients. It is especially valuable for the early diagnosis and guidance treatment of type 2 diabetes mellitus.