Objective To investigate the expression of IL-10 in serum of patients with type 2 diabetic mellitus (T2DM) and its relationship with carotid atherosclerosis.Methods Totally 168 cases of T2DM patients treated in our hospital from May 2013 to December 2016 were retrospectively analyzed.According to the IMT value,the patients were divided into the normal group,the thickening of the group and carotid atherosclerosis plaque formation group.In addition,65 cases of healthy volunteers in our hospital physical examination center at the same period were treated as control group.The levels of serum inflammation index,blood glucose,blood lipid and other indicators of all subjects were compared,at the same time,the correlation between IL-10 and other detection index was analyzed.Additionally,the risk factors of T2DM patients with carotid atherosclerosis were analyzed.Results Compared with the control group,the levels of IL-6,blood glucose,blood lipid and other indicators in T2DM patients increased significantly(P＜0.05),while the level of IL-10 decreased significantly(P＜0.05);with the increase of IMT,the levels of IL-6,blood glucose,blood lipid and other indicators in T2DM patients increased significantly,but the level of IL-10 decreased significantly,meanwhile the differences between the groups were statistically significant (P＜0.05).Compared with normal group,the levels of IL-6,blood glucose,blood lipid and other indicators of patients in thickening group and plaque group significantly elevated,but the level of IL-10 decreased significantly;the levels of IL-6,blood glucose,blood lipid and other indicators of patients in plaque group were obviously higher than those of thickening group,and IL-10 level was significantly lower than thickening group,and the differences were statistically significant (P＜0.05);the levels of IL-10 in the serum were negatively correlated with blood glucose,blood lipid and other indicators (P＜0.05);multifactor non-conditional Logistic analysis showed that IL-6,Hcy and UA were the risk factors for atherosclerosis in T2DM patients,and IL-10 was the protective factor.Conclusion The level of IL-10 of patients with T2DM is closely related to the occurrence and development of carotid artery atherosclerosis,which provides a new target for clinical treatment.