Description

Type 2 diabetes mellitus (T2DM) refers to abnormalities in glucose homeostasis characterized by insulin resistance and relative defects in insulin secretion. T2DM is often associated with microvascular and macrovascular complications.

Epidemiology

• Increased prevalence over past 3 decades
• Estimated 5,000 new cases per year in the United States
• T2DM accounts for 15–86% of newly diagnosed cases of diabetes in youth (10 to 19 years); wide variation depending on population
• Prevalence (per 1,000 youth <20 years)
  • American Indian/Alaskan Native 0.63
  • Non-Hispanic black 0.56
  • Hispanic 0.40
  • Asian/Pacific Islander 0.19
  • Non-Hispanic white 0.09

Risk Factors

• Female gender
• Adiposity
• Ethnic minorities
• Adolescence (10 to 19 years)
• Offspring of mothers with gestational diabetes
• Family history of type 2 diabetes
• History of the following:
  • Large for gestational age at birth
  • Intrauterine growth retardation
• Impaired fasting glucose
  • Fasting glucose 100 mg/dL (5.6 mmol/L) to 125 mg/dL (6.9 mmol/L)
• Impaired glucose tolerance
  • Based on 2-hour glucose from oral glucose tolerance test (OGTT; see the following) of 140 mg/dL (7.8 mmol/L) to 199 mg/dL (11 mmol/L)

Pathophysiology

• Insulin resistance
  • Major abnormality in youth with T2DM
  • Tissues (muscle, hepatic, adipose) have a decreased response to insulin, mediated by abnormal phosphorylation of insulin receptor.
• Ideally, a compensatory hyperinsulinemia develops to maintain euglycemia.
• In the presence of β-cell dysfunction, inadequate amounts of insulin are secreted to meet demands from insulin resistance.
• This relative deficiency of insulin secretion leads to hyperglycemia and diabetes.