Patients with diabetes have an increased risk of in-stent restenosis after coronary stent implantation. Serial intravascular ultrasound was used to study chronic arterial responses and edge effects after implantation of Cypher (Cordis, Johnson & Johnson, Miami Lakes, Florida) or Taxus (Boston Scientific, Maple Grove, Minnesota) stents in diabetic patients. Seventy-four diabetic patients were randomly assigned to Cypher or Taxus stent implantation. Intravascular ultrasound of 5-mm long segments immediately proximal and distal to the stent was performed after the procedure and at the 8-month follow-up. The increase in peri-stent external elastic membrane (EEM) volume was more pronounced in the Taxus group (292.4 ± 132.6 to 309.5 ± 146.8 mm3) than in the Cypher group (274.4 ± 137.2 to 275.4 ± 140.1 mm3; p = 0.005). Peri-stent plaque volume increased in the Taxus group (152.5 ± 73.7 to 166.1 ± 85.1 mm3), but was unchanged in the Cypher group (153.5 ± 75.5 to 151.5 ± 75.8 mm3; p = 0.002). In proximal and distal reference segments, mean lumen area decreased within the entire 5-mm edge segment (proximal and distal) because of plaque progression (distal, 5.5 ± 3.6 to 5.8 ± 3.7 mm2; p = 0.097; proximal, 8.1 ± 2.7 to 8.7 ± 2.9 mm2; p = 0.006) without remodeling (change in EEM) in the Taxus group. Conversely, there were no significant changes in reference-segment EEM or plaque areas in the Cypher group. In conclusion, in diabetic patients, Taxus stent implantation was associated with increased (1) peri-stent EEM volume and peri-stent plaque, and (2) stent edge plaque progression accompanied by lumen reduction without remodeling. These findings were not seen in Cypher stents.