Diabetes mellitus is a chronic disease associated with serious complications. A number of studies have suggested that enhanced oxidation is the underlying abnormality responsible for some of the complications of diabetes. It is not known whether the ingestion of antioxidant vitamins could retard or perhaps reverse the oxidative damage. The information regarding the benefit of antioxidant vitamin supplementation is conflicting; some trials have demonstrated adverse effects of excessive consumption of vitamin supplements. In this article, we review the available literature on the association of cardiovascular events and ingestion of vitamins with antioxidant properties. Given the lack of data to substantiate the benefit and safety of ingestion of antioxidant vitamins in excess of the recommended dietary allowance, physicians should avoid the recommendation of vitamin supplementation to their patients.