Most deaths and hospitalizations in patients with diabetes are related to atherosclerotic vascular disease. An asymptomatic patient with type 2 diabetes has a cardiovascular risk comparable to that of a patient without diabetes who has a history of a myocardial infarction. The American Heart Association classifies diabetes as a coronary heart disease risk equivalent. Thus, it is important in patients with diabetes to aim for systolic blood pressures less than 130 mm Hg, using an angiotensin-converting enzyme inhibitor-based regimen. The target hemoglobin A1C (HbA1C) for those patients is < 7%. New oral insulin-sensitizing medications, known as thiazolidinediones or glitazones, are useful to improve glycemic control. Most patients with diabetes require 2 or more oral agents to achieve optimal glucose control. Glitazones generally lower HbA1C by 1% to 2%. They also raise high-density lipoprotein cholesterol levels and lower triglycerides. Thus, they may potentially improve low-density lipoprotein (LDL) particle sizes by converting small, dense LDL particles into larger, less atherogenic ones. Current data concerning the lipid effects of pioglitazone and rosiglitazone are reviewed in this article.