Diabetes Mellitus, Type 2



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.


  • 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)


  • 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.

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