Oral Glucose Tolerance Test (75g Glucose)

Cleveland Heartlab G, Metabolic, O, Test

CPT Code: 82951
Order Code:  C505 (includes Glucose, Glucose 1-hour and 2-hour after 75g Glucose challenge)
ABN Requirement:  No
Synonyms: Glucose Tolerance Test; GTT; OGTT
Specimen: Serum
Volume:  1.0 mL
Minimum Volume:  0.5 mL
Container: Gel-barrier tube (SST, Tiger Top)



    1. Collect and label fasting sample according to standard protocols. The sample must be labeled with the time of draw.
    2. After administration of the prescribed dosage of glucose beverage, collect and label all subsequent timed samples as prescribed according to standard protocols. Each sample must be labeled with the time of draw.
    3. Gently invert tube 5 times immediately after draw. DO NOT SHAKE.
    4. Allow blood to clot 30 minutes.
    5. Centrifuge for 10 minutes.

Patient Preparation: Patient should be fasting for 12 hours prior to being drawn.

Special Instructions: Each timed specimen must be labeled with the draw time. Blood must be centrifuged within 30 minutes of collection.

Transport:   Store serum at 2°C to 8°C after collection and ship the same day per packaging instructions provided with the Cleveland HeartLab shipping box.


Ambient (15-25°C): 8 hours
Refrigerated (2-8°C): 7 days
Frozen (-20°C): 2 weeks
Deep Frozen (-70°): Not Acceptable

Causes for Rejection: Samples not labeled with the time of draw; samples that are grossly hemolyzed or lipemic; specimens other than serum; improper labeling; samples not stored properly; samples older than stability limits.

Methodology: Photometric

Turn Around Time: 1 to 3 days

Criteria for the diagnosis of diabetes:

Fasting Glucose65-99100-125>125
2-h Glucose*65-139140-199>199

*The test uses a glucose load containing the equivalent of 75g anhydrous glucose dissolved in water.

Critical Value:

AgeCritical Low mg/dLCritical High mg/dL
All Ages≤40≥500

Use: An oral glucose tolerance test can be used to identify diabetic and pre-diabetic individuals among a healthy, asymptomatic population.

Additional Information:  The oral glucose tolerance test can be useful in individuals with symptoms of diabetes or overweight who have had a normal glucose test.


  • American Diabetes Association “Standards of Medical Care in Diabetes 2015”
  • The Journal of Clinical and Applied Research and Education. January 2015, Volume 38, Supplement 1.

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.