This is a multicenter (19 sites), prospective, 2 arm randomized study designed to assess the safety and effectiveness of the CYPHER sirolimus-eluting stent as compared to the uncoated Bx VELOCITY balloon-expandable stent in patients with manifest diabetes mellitus. Patients with de novo native coronary artery lesions <= 42 mm in length and >=2.5mm and <=3.5mm in diameter (by visual estimate) will be included in the study. A total of 190 patients will be entered and randomly allocated to the CYPHERTM sirolimus-eluting stent or the uncoated Bx VELOCITY balloon-expandable stent at a 1:1 ratio. Patients will be followed for 12 months post-procedure, with all patients having a repeat angiography at 8 months (± 1 month).