Diabetes mellitus is important risk factor of cardiovascular diseases. Mortality of diabetics is approximately the same as mortality of non-diabetics after myocardial infarction. For this bad prognosis are responsible diabetic tissues changes (especially in blood, vessels, heart, nerves). Manifestation of acute coronary syndromes is often atypical in diabetic patients, therefore their diagnosis and treatment may be delayed. During acute myocardial ischaemia are in diabetic patients more often presented dysrythmias and congestive heart failure. The therapy is directed against ischemic pain, for lowering of ischaemic burden, slowing of progression of atherosclerosis, better quality of life, prolonging life expectancy. To iniciate the therapy of acute myocardial infarction is clinical suspicion sufficient. Antithrombogenic, antianginous and atherosclerotic plaque stabilisating therapy is given. Important is primary coronary angioplasty, in more vessel disease surgery coronary bypass. Good glycemic control is necessary for better prognosis of diabetics with acute coronary syndrome.