BACKGROUND The global burden of diabetes mellitus is increasing, and diabetes poses a serious problem for the healthcare system. We aimed to characterize patients hospitalized due to diabetes in Poland in 2019 and identify factors associated with the risk of in-hospital death and prolonged hospitalization. MATERIAL AND METHODS Data on all patients hospitalized due to diabetes in Poland in 2019 were taken from hospital discharge records collected by the National Institute of Public Health, Warsaw, Poland. The presence of comorbidities, in-hospital mortality rate, and duration of hospitalization were analyzed separately for type 1 and type 2 diabetes. RESULTS In 2019, a total of 28 617 patients were admitted to the hospital due to type 1 diabetes and 38 138 patients due to type 2 diabetes. The prevalence of comorbidities was 55.2% among patients with type 1 diabetes and 78.9% among those with type 2 diabetes. The in-hospital mortality rates were 2.1% and 3.3%, respectively. For emergency admissions, the in-hospital mortality rate was 4.0% and 4.5%, respectively. Over 30% of patients were hospitalized for more than 7 days. Older age and respiratory diseases were the most critical factors associated with higher risk of in-hospital death in patients with type 1 or type 2 diabetes (P<0.001). Male sex, age, and presence of at least 1 comorbidity were associated (P<0.001) with a higher risk of prolonged hospitalization. CONCLUSIONS Effective management of respiratory diseases in patients hospitalized due to diabetes, especially those admitted in an emergency, seems crucial to reduce the risk of in-hospital death.