ABSTRACT Objective To investigate the relationship between serum osteocalcin (OC) and carotid atherosclerosis (CAS) in middle-aged and elderly patients with T2DM. Methods A total of 430 middle-aged and elderly patients with T2DM were selected in the Department of Endocrinology in our hospital. Color Doppler ultrasound was used to detect the intima-media thickness (CIMT) of the bilateral carotid arteries, including 112 patients with normal CIMT (CIMT normal group), 106 patients with CIMT thickening (CIMT thickening group), and carotid atherosclerotic plaques There were 212 cases of lumps (CAS plaque group), and the differences in serum OC levels in each group were compared. Analyze the relationship between OC and CIMT thickening and the occurrence of CAS plaque. Results The mean OC in the CIMT thickening group (11.51±5.02) ng/ml and the mean OC in the CAS plaque group (11.59±4.23) ng/ml were significantly lower than the mean OC in the CIMT normal group (14.16±5.56) ng/ml, the difference was both There is statistical significance (P<0.01). Multivariate logistic regression analysis showed that the decrease of OC level is a risk factor for CIMT thickening and CAS plaque in middle-aged and elderly patients with T2DM. Conclusion Middle-aged and elderly T2DM patients with reduced OC levels are closely related to the risk of carotid atherosclerosis. Patients with significantly reduced OC levels should be reminded to undergo CAS screening early. KEY WORDS diabetes, type 2; middle-aged and elderly; osteocalcin; carotid artery intima-media thickness; atherosclerotic plaque