Objective To investigate the correlation between serum basic helix-loop-helix transcription fac-tor family member E40(BHLHE40)levels and subclinical atherosclerosis(SAS)in patients with type 2 dia-betes mellitus(T2DM).Methods A total of 145 T2DM patients admitted to the Department of General Prac-tice of Suzhou Municipal Hospital from January 2021 to January 2023 were selected as the study objects.Pa-tients were divided into SAS group(n=80)and non-SAS group(n=65)according to whether SAS occurred.Serum BHLHE40 level and clinical data of the two groups were compared.The correlation between serum BHLHE40 level and carotid intima media thickness(CIMT)was analyzed by Pearson correlation.The risk factors of SAS in T2DM patients were analyzed by multi-factor Logistic regression.The value of serum BHL-HE40 level in the diagnosis of SAS in T2DM patients was analyzed by receiver operating characteristic(ROC)curve.Results The age,duration of diabetes,low-density lipoprotein cholesterol(LDL-C),CIMT and serum BHLHE40 levels in SAS group were significantly higher than those in non-SAS group,with statistical differ-ence(P＜0.001).Correlation analysis showed that serum BHLHE40 level was positively correlated with CI-MT(r=0.671,P＜0.001).Multivariate Logistic regression analysis showed that duration of diabetes,age,CIMT,LDL-C and serum BHLHE40 level were all risk factors for SAS in T2DM patients(P＜0.05).ROC curve analysis indicated that the area under the curve(AUC)of serum BHLHE40 for the diagnosis of SAS in T2DM patients was 0.742,the sensitivity was 75.0％,and the specificity was 73.9％.Conclusion Serum BHLHE40 expression level is closely related to the occurrence of SAS in T2DM patients,and is of great diag-nostic value for the occurrence of SAS in T2DM patients.