Dietary modifications are recommended alongside pharmacotherapy in treating both diabetes mellitus (DM) and coronary heart disease (CHD) patients. The primary aim of our study was to assess the diet in patients with type 2 diabetes mellitus (T2DM) and myocardial infarction (MI) and to identify dietary differences between patients after the first and subsequent cardiovascular (CV) event. The secondary aim was to analyze the differences between men's and women's diets. The study population consisted of patients with DM/T2DM and MI. The research tool was the original author's questionnaire which was collected personally by a qualified dietician. The study included 67 patients with a mean age of 69 ± 8 years, hospitalized at the Silesian Centre for Heart Diseases in Zabrze in 2019. The study found that patients consumed less bread, whole-grain cereal products, fermented milk products, and vegetables than was recommended. A total of 32.8% of patients reported an intake of sweetened beverages, while 85.1% of participants consumed sweets despite being diagnosed with DM. Except for sweetened drinks, no differences in dietary behaviors were found in the patients after the first and second MI episode. Most of the included patients assessed their diet as appropriate. The dietary assessment of diabetes and myocardial infarction patients indicates that the diet does not comply with dietary recommendations, thus increasing the risk of a recurrent cardiac event despite a previous MI. No differences between the men's and the women's nutritional habits were observed.