Serial intravascular ultrasound (IVUS) studies in 55 nondiabetic patients showed that neointimal tissue proliferation after stent implantation in patients with impaired glucose tolerance (IGT) was greater than that in patients with normal glucose tolerance at follow-up. Multiple regression analysis showed that the sum of insulin levels was the best predictor of the greater neointimal index at follow-up. Another group of serial IVUS studies were performed in 62 stented lesions in 52 patients with Type 2 diabetes mellitus (DM). The study patients were randomized into a troglitazone group and a control group. The neointimal tissue proliferation at follow-up in the troglitazone group was significantly smaller than that in the control group.