This thesis discusses what diabetes mellitus is and what are the causes, risk factors, signs and symptoms of the disease. It also emphasizes the importance of conducting health education for people suffering from diabetes. In most part, it refers to the diabetic diet, which people with diabetes must strictly adhere to. The meal planning is individual for every person and it's extremely important that the person diagnosed with diabetes mellitus has trust in health workers, especially nurses, who will take care of them and pass their knowledge onto them. Nutrients intake, mediterenean diet, medical diet therapy, ketogenic diet and ADA diet are only a small part of the education. The goal of this thesis is to point out the frequency of this disease, as well as complications that can arise if the affected person doesn't follow the dietary and treatment guidelines. The purpose of the thesis is to raise awareness of the presence of diabetes in the entire population, to encourage prevention and display proper nutrition education for patients, as well as to educate the healthy population, whose knowledge of diabetes and nutrition among patients was found to be unsatisfactory by conducting a survey. The survey confirmed that knowledge exists, but the accuracy and level of knowledge varies depending on a person's occupation, education and age.