Diabetes mellitus is a metabolic disease of unknown cause. In the Republic of Croatia, there are still no accurate and precise data on the number of children affected, but it is estimated that approximately 1000 children in Croatia suffer from diabetes. Some of the early signs and symptoms of diabetes are: fatique, frequent urination, increased thirst, itchy skin and dry mouth. Clinical signs of diabetes are polyphagia, polydipsia, polyuria, severe fatique/lack of energy, weight loss and visual disturbances. There are acute and chronic complications of this disease that occur if the disease is not controlled and regulated according to the doctor's instructions. The most common acute complications that occur are diabetic ketoacidosis that occurs with severe insulin deficiency, hypoglycemia characterized by low blood glucose and hyperglycemia characterized by elevated blood glucose. Chronic coplications of diabetes occur after a long period of unregulated diabetes and are manifested by changes in blood vessels. The most common chronic complication of diabetes is diabetic foot. We distinguish two types of diabetes: type 1 and type 2. Type 1 is insulin dependent, most often children and young people and occurs much less frequently than type 2. Type 2 is insulin independent, usually occuring in adulthood, most often after the age of forty. The easiest and most commonly used test to diagnose diabetes is to determine fasting blood glucose levels and the doctor may also advise the patient to perform an oral glucose tolerance test (OGTT). In addition to insulin regular physical activity, proper diet, self control of blood glucose and perhaps most importantly education of parents and children play an important role in treatment, where the role of educators is to clarify risks and set realistic goals for improving health. Psychological support is necessary for the child, parents and the enviroment in which they live.