Background Diabetes mellitus increases adverse outcomes after coronary revascularization; however, the impact of metabolic syndrome is unclear. We examined the impact of diabetes and metabolic syndrome on coronary artery bypass graft surgery (CABG) and stenting outcomes to determine the optimal revascularization option for the treatment of complex coronary artery disease. Methods Patients (n = 1,800) with left main or three-vessel disease or both were randomly allocated to treatment with a TAXUS Express 2 paclitaxel-eluting stent (PES) or CABG, and were included in predefined nondiabetic (n = 1,348) or diabetic subgroups (n = 452); 258 patients with diabetes also had metabolic syndrome. Results Among diabetic patients, the 3-year major adverse cardiac and cerebrovascular event (MACCE) rate (22.9% CABG, 37.0% PES; p = 0.002) and revascularization rate (12.9% CABG, 28.0% PES; p < 0.001) were higher after PES treatment. Diabetes increased MACCE rates among PES-treated patients, but had little impact on results after CABG. Compared with CABG, PES treatment yielded comparable MACCE in diabetic patients (30.5% versus 29.8%, p =0.98) and nondiabetic patients (20.2% versus 20.3%, p =0.99) with low Synergy Between Percutaneous Coronary Intervention With Taxus and Cardiac Surgery (SYNTAX) study scores of 22 or less. For patients with SYNTAX Scores of 33 or greater, MACCE rates were lower with CABG (18.5% versus 45.9%, p < 0.001 diabetic; 19.8% versus 30.0%, p = 0.01 nondiabetic). Metabolic syndrome did not significantly predict MACCE or repeat revascularization. Conclusions These exploratory analyses suggest that among diabetic patients with complex left main or three-vessel disease, or both, 3-year MACCE is higher after PES compared with CABG. Although PES is a potential treatment option in patients with less complex lesions, CABG should be the revascularization option of choice for patients with more complex anatomic disease, especially with concurrent diabetes. Metabolic syndrome had little impact on 3-year outcomes.