Endothelial function and dysfunction During the past two decades, there has been an increasing recognition of the importance of normal endothelial function in the maintenance of vascular homeostasis and vascular health. Abnormalities in the function of endothelium have been recognized in a number of conditions. One of the most important abnormalities of endothelial dysfunction appears to be changes in the bioavailability of nitric oxide. It now appears clear that abnormalities in endothelial dysfunction are associated with abnormalities in the production of nitric oxide and/or abnormalities in the rate of its degradation. Either way, loss of the functional availability of nitric oxide appears to be an important characteristic of endothelial dysfunction. Endothetial dysfunction and diabetes lmpaired endothcliul-dependent vasodilatation has been described in patients with type 1 and type 2 diabetes, and the degree of impairment may correlate with glycemic control Hyperglycemia itself appears to affect multiple mechanisms that increase atherosclerosis. Hyperglycemia enhances oxidation, thrombosis, inflammation, matrix production, and the formation of advanced glycation end-products and other metabolites that can potentially damage the vasculature. Treatment of endothelial dysfunction A number of trials have demonstrated that therapy with lipid lowering agents (statins) as well as angiotensin converting enzyme inhibitors is associated with improvements in endothelial function in diabetes. These agents have also been shown to improve prognosis in patients with a number of underlying cardiac diseases and risk factors for cardiac disease. Therefore, it seems that interventions that lead to improvement in endothelial function can be associated with improvements in cardiovascular outcome. The role of antioxidant therapy is controversial. No data have been published regarding the effects of hormonal replacement therapy on endothelial dysfunction in postmenopausal women with type 2 diabetes.