This study will test the effects of insulin resistance on atherosclerosis (hardening of the arteries) in women who have systemic lupus erythematosus, more commonly known as lupus. Women with lupus have a higher chance of developing atherosclerosis than the general population, and as a result are more susceptible to heart attack and stroke. Insulin resistance is a particular risk factor for atherosclerosis, and recent small studies have shown that insulin resistance is more common in lupus patients than in those without lupus. The study will consist of a series of tests designed to assess whether there is an association between insulin resistance and atherosclerosis in women with lupus. This research may lead to further studies on possible treatments to reduce the risk of heart disease in lupus patients.