Diabetes mellitus is a major public health problem with tremendous medical and economic burdens. It is the seventh leading cause of death and the number one cause of end-stage renal disease, adult blindness, impotence, and nontraumatic lower-limb amputation in the United States. People with diabetes are 2 to 4 times more likely to suffer from stroke or from cardiovascular disease, and are twice as likely to die compared with age-matched individuals without diabetes. Diabetes cost the United States around $174 billion in 2007, $58 billion of which was related to disability, work loss, and early mortality. Although there is currently no known cure for diabetes, much progress has been made over the past 2 decades to improve the diagnosis and management of diabetes. Evidence has shown that applying aggressive interventions early can prevent or delay progression to microvascular complications that increase the mortality rate in diabetes. The authors review the guidelines for optimal evaluation of diabetes mellitus and discuss the current and emerging therapeutic options available in the United States.