Aim. The purpose of this study was to analyze the hospitalization of diabetes mellitus patients in Polish hospitals in 2005-2009. Materials and Methods. Data was taken from a nationwide database, kept at the National Institute of Public Health – National Institute of Hygiene in Warsaw. Data gathered for this work related to patients whose main cause of hospitalization was diabetes. Results. In the period of five years the number of diabetes-caused hospitalizations increased by nearly 22% – from 172.2 per 100 thousand in 2005 to 209.9 per 100 thousand in 2009. Hospital treatment covered mainly patients suffering from type 2 diabetes (116.4 per 100 thousand in 2009), as well as type 1 diabetes (87.6 per 100 thousand in 2009). Patients under 39 years of age were more often hospitalized because of type 1 diabetes, whereas in the older age groups patients were more often treated in hospitals for type 2 diabetes. Generally, in both types of the disease, older patients required hospitalizations more often than the younger ones. Cardiovascular diseases were the most reported co-morbidity in both types of the disease. In 2005-2009 the hospital mortality rate decreased with regard to both types of diabetes and an average length of hospital stay decreased by one day, reaching 8.1 days in 2009. Conclusion. It must be emphasized that the growing epidemic of diabetes and its complications are an important challenge to society. The percentage of people hospitalized due to diabetes is increasing every year and consumes significant resources dedicated to health care. Early diagnosis and appropriate treatment of diabetes are imperative, as well as reducing the disparities in access to medical care (ambulatory and stationary) for town and country residences.