The aim of the study was: evaluation of: the influence of acute phase hyperglycaemia on in-hospital and long-term prognosis in patients with acute coronary syndromes (ACS), the role of acute phase hyperglycaemia as a marker of glucose metabolism disturbances diagnosed during hospitalization and in long-term observation in patients without previously diagnosis of diabetes and analysis of adherence to non-pharmacological recommendations for lifestyle interventions in patients after ACS. A total of 307 patients were enrolled to the study. Patients were divided into three subgroups according to admission glucose level: G 1: <7.8 mmol/l (<140 mg/dl);G 2: 7.8 – 11.0 mmol/l (140 – 199 mg/dl); G 3: ≥11.1 mmol/l (≥200mg/dl). Mean observational period was 4 years. The results showed that the prevalence of glucose metabolism abnormalities in patients with myocardial infarction is high, acute phase hyperglycaemia is associated with higher incidence of adverse cardiac events during hospitalisation and is also associated with poor long-term prognosis.This relationship is particularly significant in patients without diabetes and with ST-segment elevation myocardial infarction. Acute phase hyperglycaemia is also associated with increased incidence of glucose metabolism abnormalities during hospitalization, patients with hyperglyceamia are more likely to have diabetes in future, and the level of adherence to lifestyle, diet and physical activity recommendations in patients after ACS is insufficient.