Vascular endothelium plays a major role in maintaining cardiovascular homeostasis. Nitric oxide is the most powerful vasodilating compound. Diabetes disrupts endothelial integrity through an increased oxidative stress. Recent evidence indicates that there is a strong interaction between diabetes, the secretory proteins of adipocytes, called adipokines, and endothelium. Endothelial dysfunction may precede the development of overt DM, and a prolonged and repeated exposure to postprandial hyperglycemia may play an important role in the development of atherosclerosis, even in those who have normal fasting plasma glucose levels.