AimsDiabetes is a potent risk factor for death and heart failure (HF) hospitalization following myocardial infarction (MI). Whether diabetes modifies the relationship between left ventricular ejection fraction (LVEF) and outcomes in the post-MI population is unknown. Methods and resultsThe Valsartan in Acute Myocardial Infarction trial (VALIANT) enrolled 14 703 patients with acute MI complicated by HF, systolic dysfunction, or both. We compared the risk of death, HF hospitalization, and/or recurrent MI among patients with and without diabetes using Cox proportional hazards models. To assess the relationship between diabetes, LVEF and outcomes, we assessed the relative influence of baseline LVEF on outcomes in diabetic and non-diabetic patients. Totally, 11 325 subjects (3095 diabetics) with site-reported LVEF and known diabetes status were included. At any given LVEF, diabetes was associated with a higher risk of all-cause mortality [adjusted hazard ratio (HR) 1.37, 95 CI 1.25-1.51], death or HF hospitalization (adjusted HR 1.42, 95 CI 1.31-1.51), and death or recurrent MI (adjusted HR 1.36, 95 CI 1.24-1.48). Diabetes modified the relationship between LVEF and death or HF hospitalization (P for interaction = 0.0109), such that the association between diabetes and increased risk was greater in magnitude at higher LVEF. No interaction was noted between diabetes and LVEF on risk of all-cause mortality or death or recurrent MI. ConclusionDiabetes is associated with a higher risk of death or HF hospitalization across the spectrum of LVEF in high-risk post-MI patients. The magnitude of reduction in risk of death or HF hospitalization associated with increasing LVEF is significantly attenuated among patients with diabetes when compared to patients without diabetes. © 2010 The Author.