Worse prognosis has been observed in patients with myocardial infarction (MI) and previously diagnosed diabetes mellitus (DM), new-onset DM and transient hyperglycemia compared with their non-diabetic counterparts. Many studies concerning treatment results were, however, conducted during the thrombolytic era. Relatively little is known about the outcomes of patients with elevated glucose levels during hospitalization without previous DM diagnosis or patients with new-onset DM. Our study, therefore, enclosed two additional classifications for acute MI patients in regard to glycemia status during hospitalization. We evaluated a nationwide prospective cohort of over 58 thousand MI patients in terms of inhospital complications and long-term outcomes over a three-year period per different carbohydrate disorder type: DM type 1, DM type 2, new-onset DM and transient hyperglycemia. In contrast with previous publications, this article is not only limited to admission glucose levels but includes full glycemia monitoring throughout hospitalization.