Type 2 diabetes is a growing health concern in the United States, with 20.8 million people suffering from the disease, or 7% of the population.1 It is estimated that more than 6 million of these people have not received a diagnosis of diabetes.1 Even more alarming, type 2 diabetes, often referred to as adult-onset diabetes and thought primarily to affect adults, is on the rise among children and adolescents. Early recognition of risk factors for and signs of type 2 diabetes, and screening for it in this population, can prevent the disease from developing in those with prediabetes and can slow or even reverse progression in those with the disease. This article reviews the criteria for diagnosis and provides an overview of the recommended protocol for management in patients aged 20 years and younger.
Increasing prevalence and incidence
In 2005, the CDC estimated that 176,500 people aged 20 years or younger have been given a 
diagnosis of diabetes.1 The American Diabetes Association (ADA) reports in a consensus statement that 8% to 45% of children with new diagnoses of diabetes have a nonimmune- mediated form; in the majority of these patients, this is type 2 diabetes.2 The disease disproportionately affects children of American Indian, African-American, Mexican American, and Pacific Islander ethnic backgrounds. Prior to 1994, type 2 diabetes had been diagnosed in less than 5% of patients with the disease. Since then, that percentage has risen to 30% to 50%.3
Information on the long-term effects and management of type 2 diabetes in the pediatric population is limited. Some studies, however, have focused on determining the prevalence of diabetes among specific ethnic groups. For example, in a study of the Pima Indians of Arizona, less than 1% of children aged 10 to 14 years and 2% to 3% of children aged 15 to 19 years received a diagnosis of type 2 diabetes between 1967 and 1976.4 Follow-up estimates showed that the prevalence of the disease increased; from 1987 to 1996, 2% to 3% and 4% to 5% of Pima Indian children in those age groups, respectively, received a diagnosis of type 2 diabetes.4 In a broader context, the Indian Health Service reports a 54% increase in cases of type 2 diabetes among all American Indian groups within a similar time period and in similar age groups.2 Clinic-based studies in Cincinnati indicate that the incidence of type 2 diabetes among all children increased 10 times from 1982 to 1994, and similar studies in Florida show that the prevalence increased from 9.4% to 20% between 1994 and 1998.4
In 2002, data collection began for SEARCH for Diabetes in Youth, a 5-year multicenter study funded by the CDC and the National Institutes of 
Health.5 The primary goals of this study include estimating the incidence and prevalence of diabetes among US children and adolescents by age, gender, and racial or ethnic group. Researchers aim to develop a uniform classification of types of childhood diabetes based on clinical characteristics and complications.5 Data on prevalence is currently available, but the final report is expected in 2010.
Along with the rise in prevalence of type 2 diabetes, there is an increase in obesity as well. Researchers postulate that these increases are correlated. A report from the second National Health and Nutrition Examination Survey states that 16% of children aged 6 to 19 years are considered overweight.6 The report also points out that this percentage has tripled since 1980. An estimated 85% of children with type 2 diabetes are overweight or obese when the disease is diagnosed.2 A high body mass index (BMI) is the first criteria for screening children and adolescents for type 2 diabetes.3
Clinical presentation
The pathophysiology of type 2 diabetes in children, although not completely understood, is similar to that in adults. It is characterized by 
insulin resistance in muscle, fat, and liver cells with an increase in insulin production by pancreatic beta cells. This leads to hyperinsulinemia and eventually to insulin secretion dysfunction. Impaired insulin secretion is the clinical marker for the development of type 2 diabetes.2
The clinical presentation of diabetes in children also is comparable to that of adults. Polydipsia, polyuria, and weight loss are the most frequently reported symptoms. Most patients, however, are asymptomatic.7 A definitive sign of insulin resistance is acanthosis nigricans, a velvety, hyperpigmented skin thickening found in the intertriginous areas such as the nape, axillae, and folds of the inner thigh (see Figure 1). Insulin resistance is frequently seen in patients with polycystic ovary syndrome. These patients may demonstrate hirsutism, amenorrhea or menstrual irregularities, and obesity.7
The ADA's criteria for determining which children are at risk of developing type 2 diabetes are listed in Table 1. Those patients at high risk should be screened initially at age 10 years and then every 2 years thereafter.2
Hyperglycemia develops gradually; symptoms may be subtle, and many patients are unaware that diabetes is developing. An incidental finding of glucosuria or hyperglycemia leads to the diagnosis in up to 50% of cases.7 A fasting plasma glucose test is preferred over an oral glucose tolerance test because the former is more convenient and less expensive. A diagnosis of type 2 diabetes is made when a random glucose level is higher than 200 mg/dL, the fasting glucose level is higher than 126 mg/dL, or the 2-hour postprandial glucose level is higher than 200 mg/dL.2 Elevated insulin and Cpeptide levels with no autoantibodies to islet cells or insulin indicates type 2 disease. 