Background Various studies revealled that preconditioning and postconditioning protects the heart against myocardial ischemic/reperfusion injury. Diabetes mellitus is an independent high risk factor to ischemic heart disease and aggravates the long-term outcome. Recent studies found that diabetes mellitus might impair myocardial protective effects by blocking myocardial preservation mechanisms. Objective This review focused on the effects of diabetes mellitus on myocardial preconditionging/post-conditioning and its possible mechanisms. Content The possible mechanisms includ the influence of diabetes mellitus on cardiovascular disease, the effects of diabetes mellitus on myocardial ischemic/reperfusion injury as well as the effects of diabetes mellitus on myocardial preconditioning/ postconditioning and the possible mechanisms. Trend Though the impact of diabetes mellitus on myocardial preconditioning/ postconditionging is controversial and the cellular mechanisms remains abscure, the improvement of the outcome and survival rate of diabetes patients and the exploration of ideal protective cardio agents still needs further studies..