Lab

Glucose Tolerance Test 2 hour

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Glucose Tolerance Test 2 hour, Two hour Glucose Tolerance Test, OGTT

  • See Also
  1. Diabetes Screening
  2. Gestational Diabetes
  • Indications
  1. Gestational Diabetes Screening
    1. Alternative to standard 2 step screening (GCT followed by GTT)
  2. Diagnosis of Diabetes Mellitus (rarely indicated)
    1. Replaced by Fasting Serum Glucose >126 mg/dl (and Hemoglobin A1C >6.5%)
    2. May be useful in Insulin Resistance
  • Protocol
  1. Administer 75 grams Glucola drink
  2. Measure Serum Glucose hourly over 2 hour period
  • Interpretation
  • Non-Pregnant
  1. Elevated values must include 2 hour Glucose
  2. Two Glucose values (at one and two hours) >200 mg/dl
    1. Consistent with Diabetes Mellitus
  3. Either Value >140 mg/dl
    1. Consistent with Impaired Glucose Tolerance
  • Interpretation
  • Pregnancy
  1. Gestational Diabetes criteria met if either Glucose abnormal at 1 or 2 hours
  2. Normal Glucose Values
    1. Fasting Glucose <=92 mg/dl (5.11 mmol/L)
    2. One Hour Glucose <= 180 mg/dl (9.99 mmol/L)
    3. Fasting Glucose <= 153 mg/dl (8.49 mmol/L)
  • References
  1. Saccone (2020) J Matern Fetal Neonatal Med 33(9): 1616-24 [PubMed]