Abstract The diploma thesis is focused on the application of insulin in nursing practice. In 2013, there were 678,935 patients with diabetes mellitus in the Czech Republic. Of this, 17.5 % of patients were treated with insulin. When applying insulin, we must observe certain principles and procedures to avoid complications. The diploma thesis consists of the theoretical and research part. The theoretical part describes the characteristics of diabetes mellitus, describes insulin and its history, regimens, types and storage of insulin. It is also focused on the insulin application process and the education of patients. In relation to the topic, two objectives were set. The first objective was to find out how to apply insulin in nursing practice based on evidence. The second objective was to find out how the nursing process is provided by a nurse when applying insulin in nursing practice. Following these objectives, two research questions have been identified. First research question: How is insulin applied in nursing practice? The second research question: How is the nursing process filled with the insulin application? The practical part was elaborated using a qualitative research survey. The research was carried out using two variants of a semi-structured interview. The first variation of the interview was for insulin-like patients. The second variant was intended for general nurses from standard departments of selected hospitals and for nurses working in diabetological outpatient clinics. The first set consisted of ten respondents, of which 5 were women and 5 men. The second group consisted of 9 respondents, of whom all were women. The conversations were recorded and then literally overwritten. Interviews were overwritten using the pencil-paper method and further analyzed by Open Encoding. Based on data analysis, 5 categories were created with several subcategories for patients and 6 categories with several subcategories for nurses. Based on the analysis of the data, it can be said that patients or nurses do not apply insulin completely correctly. I perceive the basic problem in the distribution of insulin by species and its correct application, which varies for each species. I see another problem in incorrect application according to the length of the needle, such as the angle of the needle and the formation of the skin kelp. The output of the diploma thesis will be the standard of nursing care based on EBP, in order to highlight the shortcomings we found in the research investigation and to prevent their prevention. This standard aims to refine and improve the care provided.