Diabetes mellitus arises due to a metabolic disorder that leads to a state known as hyperglycemia, an increased concentration of glucose in the blood. It is a major public health problem, and the number of newly diagnosed patients is growing every year. Diabetes can occur at any age, childhood being no exception. The Republic of Croatia is in the group of countries with a high risk of developing type 1 diabetes. The main „culprit“ for the development of the disease is the pancreas, a gland that secretes the hormone insulin. Insulin binds to the cell surface and thus allows glucose to enter the cells enabling their proper function. In addition to observed symptoms, it is important to make diagnostic testing to insure that person has diabetes. Given that the disease is often present in children, it’s manifestation and impact on daily functioning are different (than in adults) and sometimes a help of a psychologist is required. After diagnosis, a treatment based on insulin administration, regular self-monitoring, proper diet and adequate physical activity is prescribed. With the help of new technologies, living with diabetes is much easier. Insulin pump enables stimulation of the physiological secretion of insulin and makes life easier for children and parents; while devices for continuous glucose monitoring, the commonly named CGM devices allow, at any moment, knowledge of the current glycaemic level. Proper diet and physical activity also play an important role in keeping the disease under control, preventing further progression of the diabetes or any related complications. Therefore, it is important to educate patient and his family about the diabetes mellitus from the first diagnosis. Major role in the disease treatment has a nurse, who must possess certain competencies and knowledge in order to establish trustworthy patient-nurse relationship together with best possible disease control.