Aim To observe the relationship between carotid atherosclerosis (CAs) and coronary arterial atherosclerosis (CAAs) in patients complicated with diabetes mellitus (DM). Methods Coronary arteriography was performed in 73 patients with diabetes mellitus to judge the degree of CAAs. The carotid intima-media thickness(IMT) and carotid plaques were measured by ultrasound. Results There was significant difference between CAAs group with DM in IMT, carotid plaques score and incidence of carotid atherosclerosis plaques (p<0.001,p<0.005,p<0.01). There was positive correlation between rami of CAAs with DM and IMT, carotid atherosclerosis score (r=0.71,0.68, p<0.001). There was positive correlation between coronary arteriography score and IMT, carotid atherosclerosis score (r=0.69, 0.66, p<0.001). Conclusion There was close relationship between CAs and CAAs in patients of coronary heart disease complicated with diabetes mellitus.