Aim To investigate the correlation between serum soluble programmed cell death-1 (sPD-1) and carotid atherosclerosis (CAS) plaque in patients with type 2 diabetes mellitus (T2DM). Methods 87 patients with T2DM were selected as the study subjects, and 33 cases with normal glucose tolerance were selected as the control group.According to the presence or absence of CAS plaque, T2DM patients were divided into two groups:40 cases in T2DM without CAS group and 47 cases in T2DM with CAS group. Serum sPD-1 concentration and biochemical parameters were detected and compared in each group. The correlation between sPD-1 and each index was analyzed. ROC curve was used to analyze the predictive value of sPD-1 for T2DM with CAS plaque. Results The concentration of sPD-1 in T2DM without CAS group was significantly higher than that in control group (P＜0.05). The concentration of sPD-1 in T2DM with CAS group was significantly higher than that in control group and T2DM without CAS group (P＜0.05). SPD-1 was positively correlated with age, waist-hip ratio, triglyceride, fasting blood glucose, glycosylated hemoglobin A1, fasting insulin and high-sensitivity C-reactive protein (P＜0.05), negatively correlated with gender (male as reference), high density lipoprotein cholesterol and lipoprotein(a) (P＜0.05). ROC analysis indicated that the diagnostic value of sPD-1 in T2DM with CAS plaque formation was moderate (P＜0.05). Conclusion Serum sPD-1 may be involved in the formation and development of T2DM and atherosclerotic plaque, and it has predictive value for T2DM with CAS plaque formation.