Type 2 diabetes mellitus, a significant cause of adult morbidity and mortality, is being diagnosed more frequently in children and adolescents. Genetic predisposition and environmental factors are important determinants for the expression of this disease. Blacks, Hispanic Americans, and Native Americans are known to be at higher risk for type 2 diabetes mellitus as adults and there appears to be increased prevalence of the disease in adolescent members of these groups. Obesity, sedentary lifestyle, and high-fat diet are associated with type 2 diabetes mellitus. A combination of peripheral insulin resistance and relative insulin deficiency results in chronic hyperglycemia. The onset of hyperglycemia is usually slow and symptoms such as polyuria and polydipsia are often subtle and may go unrecognized by the patient. The treatment of children and adolescents with type 2 diabetes mellitus is an area of active study. Programs targeting diet modification and increased physical activity are being developed in hopes of delaying or preventing the onset of disease. This paper examines risk factors for the development of type 2 diabetes mellitus, reviews diagnostic criteria, and discusses newly established screening criteria for type 2 diabetes mellitus in children and adolescents.