Importance  Chronic diseases have overtaken acute diseases, such as infections, as the major cause of premature mortality worldwide. Diabetes mellitus, a chronic degenerative metabolic disease, has reached epidemic proportions in the past 30 years, with worldwide prevalence approaching 400 million people.

Observations and Advances  The epidemic is largely secondary to an increasing sedentary lifestyle and highly prevalent overweight and obesity contributing to the development of type 2 diabetes. Clinical research efforts have developed and demonstrated effective strategies for prevention, and the annual incidence of diabetes in the United States may be decreasing for the first time in 3 decades. The long-term complications of diabetes cause severe morbidity and mortality. Here too the means of reducing the burden of microvascular and cardiovascular disease have been proved.

Conclusions and Relevance  Improved glycemic control and better management of other identified risk factors for the complications of diabetes and more effective treatment of cardiovascular disease and microvascular complications have resulted in a more optimistic outlook for people with diabetes. This review focuses on recent advances in diagnosis and management and the remaining challenges in the prevention and treatment of diabetes mellitus.