Diabetes mellitus is one of the most common noncommunicable diseases worldwide. In the Eastern Mediterranean Region, there has been a rapid increase in the incidence of diabetes mellitus and it is now the fourth leading cause of death. These guidelines provide up-to-date, reliable and balanced information for the prevention and care of diabetes mellitus in the Region. The information is evidence-based and clearly stated to facilitate the use of the guidelines in daily practice. They are intended to benefit physicians at primary, secondary and tertiary level, general practitioners, internists and family medicine specialists, clinical dieticians and nurses, as well as policy-makers at ministries of health. They provide the information necessary for decision-making by health care providers and patients themselves about disease management in the most commonly encountered situations.