Patient selection and vitamin E treatment in diabetes mellitus.

In diabetes, there is an increase in oxidative stress due to elevated glucose levels in the plasma. High glucose promotes glycosylation, of both plasma and cellular proteins, which particularly affects the endothelial-cell lining of the blood vessel wall and interferes with its normal function. Thus, diabetes mellitus patients suffer from a higher incidence of cardiovascular complications such as atherosclerosis as compared with the nondiabetic population. Haptoglobin (Hp) is a plasma protein that binds free hemoglobin and prevents heme-iron mediated oxidation. There are three different types of Hp, which differ in their antioxidant ability. Several clinical studies have shown that the Hp 2-2 genotype is associated with higher incidence of cardiovascular diseases among diabetics. Vitamin E, a low-cost, easy-to-use antioxidant, was found to decrease the risk of developing cardiovascular diseases in Hp 2-2 diabetic patients. This review summarizes several studies that show the importance of vitamin E supplementation in a specific subgroup of patients, diabetic individuals carrying the Hp 2-2 genotype.