A total of 75 patients will be recruited: 25 for each arm of the study. Each arm evaluates the potential benefit of a particular medication and will enroll sequentially. An endothelial function test will be performed on an outpatient basis. The first 25 patients will be assigned at random to receive pravastatin sodium or placebo; the next 25 will receive gemfibrozil or placebo; the final 25 will receive rosiglitazone or placebo. Patients will take the pills for 6 weeks, no pills for the next 4 weeks, and then the opposite treatment for 6 more weeks. Two weeks after the start of the study drug, blood will be taken to check for potential toxic side effects. After each 6-week treatment, blood will be drawn and endothelial function tests will be performed.