Effects of macronutrient excess and composition on oxidative stress: relevance to diabetes and cardiovascular disease.

Type 2 diabetes is a disease that is increasing in prevalence worldwide. In genetically predisposed patients, the combination of excess caloric intake and reduced physical activity induces a state of insulin resistance. When beta-cells are not able to compensate for insulin resistance by adequately increasing insulin production, impaired glucose tolerance occurs, which is characterized by excessive postprandial hyperglycemia. Impaired glucose tolerance may evolve into overt diabetes. These three conditions (ie, insulin resistance, impaired glucose tolerance, and overt diabetes) are associated with an increased risk of cardiovascular disease. Intervention trials have demonstrated that diabetes can be prevented by means of lifestyle modifications, antidiabetic drugs directed against insulin resistance or simply postprandial hyperglycemia, and cardiovascular drugs devoid of effects on blood glucose levels. All of these have intracellular antioxidant effects. Evidence on the efficacy of antioxidant interventions is accumulating, and oxidative stress may be a therapeutic target to prevent diabetes as well as cardiovascular complications.