Aims: Data regarding the impact on clinical outcomes of PCI with DES implantation vs. CABG to treat unprotected left main coronary artery (ULMCA) disease in diabetic patients are still insufficient. The present study evaluated the short-term and long-term results of percutaneous and surgical revascularisation in diabetic patients with ULMCA disease in a large population. Methods and results: A total of 826 diabetic patients with ULMCA stenosis who received DES (n=520) or underwent CABG (n=306) were selected and analysed from the DELTA registry. In-hospital MACCE was significantly higher in the CABG group, mainly driven by a higher incidence of MI. At four-year follow-up, freedom from death and the composite endpoint of death, MI and cerebrovascular accident (CVA) was similar in the two treatment groups (CABG 87.4%, PCI 82.5%, p=0.124, and CABG 85.4%, PCI 78.9%, Conclusions: In diabetic patients with ULMCA disease with/without concomitant multivessel disease, PCI and CABG led to similar results in terms of death, MI and CVA. However, CABG was associated with less MACCE at long-term follow-up, primarily due to the higher repeat revascularisation rate with DES.