Diabetes mellitus is a metabolic disease characterized by hyperglycemia. It stems from defects, which are formed in insulin secretion, insulin effect or both caused by interactions of genetics, environmental factors and life style changes. As well as being a very serious and progressive disease, we face it as a major health problem for both individuals and society for it adversely affects the mortality and morbidity by causing chronic and acute complications in case of lack of control. Maximum effort should be made in order to prevent diabetes in all sections of society. Family medicine doctors have the greatest part in this regard for their unique roles in primary care. Therefore, primary care health personnel should evaluate the patients in terms of diabetes risk factors, take the preventive measures against development of diabetes and do diabetes screening for required individuals. They should follow up the treatments and controls of the patients having diabetes in order to avoid complications. Since prevention and treatment requires a multi-disciplinary approach, they should to refer patients to nephrology, ophthalmology, cardiology etc. departments. To this end, diabetes and approach to diabetic patients have been examined in this article.