Glucose tolerance, 2 hr standard (non-pregnant patients)-240

Test info

Glucose tolerance, 2 hr standard (non-pregnant patients)

The standard 2 hour glucose tolerance test is useful for screening for type 2 diabetes in non-pregnant patients.



Fasting is required prior to sample collection

Fasting for a blood test

Lithium heparin (Li hep) plasma
1.0 mL
  1. Draw a fasting specimen
    • Immediately following collection, mix sample thoroughly by gentle inverting 8 - 10 times to prevent clotting
    • If the fasting glucose is >126, cancel the testing as not indicated and notify the ordering physician
  2. Give fasting patient 75 gm glucose solution
    • Must be consumed within 10 minutes
  3. Draw second specimen at 2 hours
  4. Label with time and hour collected

Spin within two (2) hours of sample collection




Lt green plasma separator (PST)

Sodium fluoride (Na Fl) whole blood or plasma
EDTA plasma


  1. Allow sample to clot for a minimum of 30 minutes
  2. Spin within two (2) hours of sample collection

Dk green/lavender: 

  1. Spin
  2. Transfer the plasma to an AHL False Bottom Plasma/Serum Transport Tube labeled as the appropriate plasma type, within two (2) hours of sample collection


If a grey top tube will not reach the Central Laboratory within 24 hours of collection, it should be spun down, and the plasma transferred to an AHL False Bottom Plasma/Serum Transport Tube labeled as NaFl plasma. 

Additional testing cannot be added on to this sample.


Gold serum separator (SST) tube

Grey Sodium flouride (NaFl) or

False bottom plasma/serum transport vial/tube (AHL)




Refrigerated  - 7 days

NaFl whole blood:

Refrigerated - 24 hours




Refrigerated - 3 days

Ambient - 8 hours


  • Improper labels (unlabeled or mislabeled)
  • Hemolysis (some procedures)
  • Improper anticoagulant or ratio
  • Delay in transport
  • Improper storage temperature affecting results
  • Inappropriate timing of collection
  • Improper container
  • Leaking container resulting in compromised specimen
  • Quantity not sufficient (QNS)


AHL - Chemistry: C
1 day


Clinical and Interpretive info

Fasting: 65 - 100 mg/dL
1 hr:      65 - 200 mg/dL
2 hr:      65 - 140 mg/dL

The 2-hour glucose tolerance protocol for gestational diabetes is not orderable or supported at Allina Health. This is to ensure that all pregnant patients receive the same standard of diagnostic care. The gestational GTT tests available from our laboratory are the Glucose, gestational screen and the Glucose tolerance, 3 hour gestational, recommended by the American College of Obstetrics and Gynecology (ACOG). If a 2-hour gestational GTT is requested, the provider must be contacted to either (1) place a new order for the Glucose gestational screen (1-hour); or, (2) direct the patient to a different laboratory for administration of the 2-hour protocol.


82947 - Fasting glucose
82950 - Glucose post dose