Description 


  • Metabolic findings between normal glucose homeostasis and diabetes 


Also called 


  • Impaired glucose tolerance (IGT) 

  • Impaired fasting glucose (IFG) 

  • Impaired fasting glycemia 

  • Abnormal glucose tolerance 

  • Glucose intolerance 

  • Latent diabetes 


ICD-9 codes 


  • 790.21 impaired fasting glucose 

  • 790.22 impaired glucose tolerance test (oral) 

  • 790.29 other abnormal glucose 


Definitions 


  • Prediabetes defined as any of 

    – IGT: Defined as 2-hour 75 g oral glucose tolerance test levels 140-199 mg/dL (7.8-11 mmol/L); normal
      levels on this test <140 mg/dL (7.8 mmol/L) 

    – IFG: Defined as fasting plasma glucose levels 100-125 mg/dL (5.6-6.9 mmol/L); normal fasting glucose
      <100 mg/dL 
(5.6 mmol/L) 

    – Hemoglobin (Hb) A1c 5.7%-6.4% (may be less sensitive than IGT or IFG)


Epidemiology 


  • Prevalence increasing

    – 9.7% prevalence among U.S. adults aged 40-74 years (1988-1994) 

    – 26% prevalence among U.S. adults aged >20 years (1999-2002) 


Causes 


  • Insulin resistance

    – Obesity (most common cause)

    – Type B insulin resistance

  • Insufficient insulin secretion (beta-cell dysfunction)
    – Possible accelerated age-related loss of beta-cell function 


Likely risk factors 


  • Risk factors for diabetes 

    – Metabolic conditions: Obesity/metabolic syndrome; polycystic ovary syndrome (PCOS)
; gestational diabetes 

    – Modifiable lifestyle factors: Dietary factors; lack of exercise; smoking 

    – Demographic factors; Race/ethnicity: Blacks and Hispanics (in the United States) 
and aborigines (in Australia); lower socioeconomic status 


Prognosis 


  • IGT and IFG associated with increased risk of

    – Progression to diabetes mellitus (DM)

    – Mortality

    – Cardiovascular disease