Diabetes, a metabolic disease of hyperglycemia, is one of the most common metabolic diseases, resulting in increased morbidity and mortality worldwide. The prevalence of diabetes mellitus in Korea is dramatically increasing, especially among younger people. Diabetes has considerable variations depending on ethnicity, culture, socioeconomic status, and genetic susceptibility. In this context, the Korean diabetes association (KDA) revised the clinical practice guideline for diabetes in 2011 based on a review and analysis of all of the related literature, in order to attenuate the rapid increase in prevalence and prevent complications. This review outlines the updated clinical recommendations for screening, diagnosis, monitoring, and management including nutrition therapy, physical activity, pharmacologic treatment, epidemiologic trends, risk factors, and the pathophysiology of diabetes. We then emphasize the importance of diabetes treatment according to a patient's characteristics. (SMN 2011;2:52-58)