Abstract Aims The aim of this article was to compare rates of all-cause death at 10 years following coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI) in patients with or without diabetes. Methods and results The SYNTAXES study evaluated up to 10-year survival of 1800 patients with three-vessel disease (3VD) and/or left main coronary artery disease (LMCAD) randomized to receive either PCI or CABG in the SYNTAX trial. Ten-year all-cause death according to diabetic status and revascularization strategy was examined. In diabetics (n = 452), the risk of mortality was numerically higher with PCI compared with CABG at 5 years [19.6% vs. 13.3%, hazard ratio (HR): 1.53, 95% confidence interval (CI): 0.96, 2.43, P = 0.075], with the opposite seen between 5 and 10 years (PCI vs. CABG: 20.8% vs. 24.4%, HR: 0.82, 95% CI: 0.52, 1.27, P = 0.366). Irrespective of diabetic status, there was no significant difference in all-cause death at 10 years between patients receiving PCI or CABG, the absolute treatment difference was 1.9% in diabetics (PCI vs. CABG: 36.4% vs. 34.5%, difference: 1.9%, 95% CI: −7.6%, 11.1%, P = 0.551). Among insulin-treated patients (n = 182), all-cause death at 10 years was numerically higher with PCI (47.9% vs. 39.6%, difference: 8.2%, 95% CI: −6.5%, 22.5%, P = 0.227). Conclusions The treatment effects of PCI vs. CABG on all-cause death at 10 years in patients with 3VD and/or LMCAD were similar irrespective of the presence of diabetes. There may, however, be a survival benefit with CABG in patients with insulin-treated diabetes. The association between revascularization strategy and very long-term ischaemic and safety outcomes for patients with diabetes needs further investigation in dedicated trials. Trial registration SYNTAX: ClinicalTrials.gov reference: NCT00114972 and SYNTAX Extended Survival: ClinicalTrials.gov reference: NCT03417050.