Abstract: Objective To investigate the effect of dapagliflozin on blood cholesterol and carotid intima-media thickness（CIMT） in patients with type 2 diabetes mellitus（T2 DM）. Methods A total of 208 T2 DM patients prooly reacted to 3 months treatment of metformin were recruited during May 2017 to June 2020 in the Department of Endocrinology, Quanzhou First Hospital Affiliated to Fujian Medical University and divided into 2 groups（104 for each group） by random number table. Patients in dapagliflozin group and sitagliptin group were given dapagliflozin 10 mg and sitagliptin 100 mg once a day, respectively, for 24 weeks. Weight, waist hip ratio, fasting plasma glucose, glycosylated hemoglobin A1 c（HbA1 c）, homeostatic model assessment of insulin resistance（HOMA-IR）, systolic blood pressure, diastolic blood pressure, triacylglycerol, total cholesterol, high density lipoprotein cholesterol（HDL-C）, low-density lipoprotein cholesterol（LDL-C）, small dense low-density lipoprotein cholesterol（sdLDL-C）, uric acid, interleukin-6（IL-6）, superoxidedismutase（SOD）, homocysteine（Hcy） were assessed before and after the treatment. Results HbA1 c, fasting plasma glucose, HOMA-IR, IL-6, SOD and Hcy were all decreased in the two groups after treatment（P＜0.05）. CIMT in both groups decreased dapagliflozin group: after treatment（0.88±0.20） vs before treatment（1.18±0.11） mm, t=15.204, P＜0.01; sitagliptin group: after treatment:（1.10±0.11） vs before treatment:（1.19±0.12） mm, t=7.979, P＜0.01, which was more significantly in dapagliflozin group than in sitagliptin group -0.30（-0.40 to-0.20） vs-0.10（-0.20 to 0） mm, t=-8.130, P＜0.01. There was no significant difference in the decrease of HbA1 c and fasting plasma glucose between the two groups（P＞0.05）. Compared with sitagliptin group, HOMA-IR, CIMT, IL-6, SOD and Hcy in dapagliflozin group improved more significantly（P＜0.05）. The level of LDL-C increased in dapagliflozin group（P＜0.05）, while sdLDL decreased（P＜0.01）, and the level of LDL-C and sdLDL did not change in sitagliptin group（P＞0.05）. There was no withdrawal in the two groups. There were 2 cases of first-degree hypoglycemia in each group, and no other side-effects were recorded. Conclusion Dapagliflozin can reduce sdLDL and CIMT in type 2 diabetic patients.