The purpose of the study is to determine if the addition of rosiglitazone to subjects with
fair glucose control on other oral agents improves endothelial function, a surrogate marker
of vascular health.
It is hypothesized that improving whole body insulin sensitivity with combination therapy
including rosiglitazone will restore the vascular actions of insulin and improve
endothelium-dependent vasomotion more effectively than placebo in patients with diabetes
mellitus.