Abstract 2365: Pharmacogenomic Application Of The Haptoglobin Genotype To Identify Individuals With Diabetes Mellitus Who Benefit From Vitamin E Supplementation: A Prospective Randomized, Double-blind, Placebo Controlled Trial

Background. Large clinical trials of antioxidant therapy with vitamin E have failed to demonstrate a decrease in cardiovascular events. However, these studies did not address possible benefit to subgroups with increased oxidative stress. Haptoglobin (Hp), a major anti-oxidant protein, is a determinant of cardiovascular events in patients with diabetes mellitus (DM). The Hp gene is polymorphic with two common alleles, 1 and 2. The Hp 2 allelic protein product provides inferior anti-oxidant protection as compared to the Hp 1 allelic product. In a retrospective analysis of HOPE participants with DM and the Hp 2–2 genotype, vitamin E significantly reduced the incidence of myocardial infarction and cardiovascular death. We sought to validate this observation in a prospective trial. Methods and Results. 984 DM individuals with the Hp 2–2 genotype were randomized and treated with either natural source vitamin E (400IU/day) or placebo. The primary composite outcome was non-fatal myocardial infarction, stroke and cardiovascular death. The study was intended to last 4 years with initial evaluation of endpoints scheduled 12 months after enrollment of the first patient. At the initial evaluation, the primary composite outcome was significantly reduced in patients receiving vitamin E compared to placebo (1.0% vs. 3.8%, p=0.004). This was predominately due to a significant decrease in the incidence of non-fatal myocardial infarction (0.2% vs. 2.1%, p=0.004) and led to early termination of the study. Conclusions . Vitamin E supplementation appears to reduce cardiovascular events in individuals with DM and the Hp 2–2 genotype. (ClinicalTrials.gov number NCT00220831 ).