Until recently, diabetes in children was virtually synonymous with type 1 diabetes mellitus, whereas type 2 diabetes was a disease of middle age and the elderly. Over the past 10-20 years, an alarming increase in the prevalence of type 2 diabetes has been reported from pediatric diabetes centers in North America and elsewhere in the world. Lifestyle factors responsible for the worldwide epidemic of overweight and obesity are responsible for the increase in the prevalence of type 2 diabetes in adults and children. This article briefly discusses the diagnosis and major types of diabetes in children but focuses on aspects of type 2 diabetes in children and adolescents, including demographics, pathophysiology, clinical presentation, screening, prevention and treatment. The identification of children at risk for type 2 diabetes and the implementation of community-wide preventive programs will be essential to reverse the tide. The availability of calorie dense "fast foods," candy, and sugared soft drinks must be restricted in schools and other venues frequented by children. Parents must limit the amount of time their children spend watching television and playing computer games. After-school programs that promote physical activity should be a priority of local and central governmental agencies. Prevention will only succeed if governments and local communities recognize that childhood obesity is an important public health problem and provide an environment that promotes changes in lifestyle that prevent and reverse obesity.