T2DM has dramatically increased throughout the world in many ethnic groups and among people with diverse social and economic backgrounds. Over the last decade, the increase in the number of children and youth with T2DM has been labeled an "epidemic". Before the 1990s, it was rare for most pediatric centers to have patients with T2DM. By 1994, T2DM patients represented up to 16% of new cases of diabetes in children in urban areas, and by 1999, depending on geographic location, the range of percent of new cases due to T2DM was between 8-45% and disproportionately represented in minority populations.

T2DM in children and youth, as in adults, is due to the combination of insulin resistance and relative β-cell failure. It appears that there are a host of genetic and environmental risk factors for insulin resistance and limited β-cell reserve. The epidemic of pediatric T2DM is coincident with the rise in the number of children who are overweight or at risk for overweight and with a decrease in the physical activity pattern of youth. There has been a strong association between T2DM and the onset of puberty, a positive family history of T2DM, and elements of the metabolic syndrome such as acanthosis nigricans and polycystic ovarian syndrome (PCOS).

Preceding the development of frank diabetes, children and youth experience a period of prediabetes. Prediabetes is defined as either elevated fasting glucose or impaired glucose tolerance. Despite the dramatic increase in the number of cases of prediabetes and T2DM in pediatric populations, there have been no published large-scale studies investigating the pathophysiology, treatment, and complications of these disorders in children and youth. The long-term complications and costs associated with T2DM make such studies imperative. Between 1997 and 2002, the estimated cost of diabetes with regard to direct medical cost increased from $44 billion to $92 billion, and the total cost increased from $98 billion to $132 billion. The vast majority of monies are spent on the long-term complications of this disorder. Since the long-term microvascular and cardiovascular complications relate to duration of diabetes and to control of glycemia, it could be hypothesized that the increasing number of children and youth diagnosed with T2DM, if not effectively treated, could dramatically add to the economic burden of this disease over the ensuing decades.

Except in American Indian youth, there are no population-based data available with regard to prevalence of T2DM. Instead, only clinic-based reports indicate that there has been a tremendous increase in the number of children and adolescents with T2DM. T2DM occurs almost exclusively in children and youth who are overweight or at risk for overweight (BMI \> 85th percentile for age). At the time of diagnosis, most pediatric patients are in the midst of Tanner Stage 2-4 puberty. Puberty contributes to insulin resistance due to augmentation of growth hormone secretion, and if these normal pubertal physiologic changes are not compensated for by increased insulin secretion, frank diabetes will develop. Half to three-quarters of patients have a parent and close to ninety percent have at least one first or second degree relative with T2DM. The clinical presentation of T2DM in youth ranges from mild asymptomatic hyperglycemia to severe ketoacidosis. In those who present with clinical symptoms due to hyperglycemia, glycosuria and weight loss are present in 20-40%, ketonuria is present in 33% and ketoacidosis is found in 5-10%. Patients without clinical symptoms are diagnosed as the result of routine blood or urine testing during a health care visit or by investigating a variety of complaints such as chronic infection, sleep apnea, hyperlipidemia, hypertension, and hirsutism or irregular periods associated with PCOS. It may be difficult to distinguish T1DM from T2DM at presentation. The absence of autoantibodies is a prerequisite for the diagnosis of T2DM. In addition, evidence of residual insulin secretion is suggestive of T2DM rather than T1DM.

Patients with T2DM have dual abnormalities of insulin resistance and insulin deficiency. It is hypothesized that to achieve the level of glycemic control required to optimize long-term outcome and decrease or prevent microvascular complications, treatment regimens should theoretically be designed to improve insulin resistance and preserve residual β-cell function. The available anti-diabetic agents have not been adequately evaluated in pediatric patients. This is particularly relevant with regard to using combination therapy to improve glycemic control or lifestyle interventions aimed at obesity and sedentary behavior.