BACKGROUND: This study aimed to compare differences in the risk factors and clinical outcomes of type 2 diabetes mellitus (DM) and non-DM patients with de novo lesions (DNL), definite in-stent restenosis (ISR), and late or very late stent thrombosis (LST/VLST). METHODS: A total of 4151 patients with acute coronary syndrome were screened angiographically to determine DNL, ISR, and LST/VLST. A total of 3976 patients were included in the analysis and divided into DM (n=1302) or non-DM (n=2674) group at admission. The primary endpoint was a composite of major adverse cardiovascular events (MACEs), defined as death, myocardial infarction, revascularization, and ischemic stroke within a 1-year follow-up period. RESULTS: In the group with total white blood cell count >10 10^9/L (p=0.004), neutral granular cell count >7 10^9/L (p=0.030), neutrophil-lymphocyte ratio >1.5 (p=0.041), DNL outperformed LST/VLST lesions in terms of revascularization at a median follow-up of 698 days. Among patients with DNL, the incidences of MACEs (log-rank p=0.0002), all-cause death (log-rank p=0.00032), cardiac-related death (log-rank p=0.021), and revascularization (log-rank p=0.029) were significantly lower in the non-DM group than in the DM group. However, no difference was observed in the event rates of endpoints among patients with ISR and LST/VLST between the non-DM and DM groups. Furthermore, among DM patients, there was a critically higher cumulative incidence of revascularization (log-rank p=0.0002) in the subgroup with ISR lesions and higher rate of ischemic stroke (log-rank p=0.033) in the subgroup with LST/VLST lesions. CONCLUSION: This study found that DM patients have a higher incidence of composite clinical outcomes than non-DM patients among patients with DNL. Compared with patients with DNL, patients with ISR lesions and LST/VLST lesions had more incidence of revascularization by long-term follow up. Thus, ISR and LST/VLST lesions are critical problems after coronary stenting, especially among DM patients.