CPT Code: 82951 (3 samples; Fasting, 1 hour, 2 hour)
Each additional sample: 82952
Order Code Options:
OGTT, 3 Samples (Fasting, 1 hour, 2 hour): C505
OGTT, 2 Samples (Fasting, 1 hour): 1368
OGTT, 2 Samples (Fasting, 2 hour): 1369
OGTT, Additional Glucose 1: C506
OGTT, Additional Glucose 2: C540
ABN Requirement: No
Synonyms: Glucose Tolerance Test; GTT; OGTT
Acceptable Specimen Types:
Serum collected in separate gel-barrier (SST, Tiger Top) tubes for each specific draw time
Plasma collected in separate fluoride/oxalate (Gray Top) tubes for each specific draw time
Whole blood collected in separate fluoride/oxalate (Gray Top) tubes for each draw time
Note: Whole blood gray top samples are not recommended due to short stability time
Volume: 1.0 mL per individual sample
Minimum Volume: 0.5 mL per individual sample
Container: Gel-Barrier Tube (SST, Tiger Top) or Gray Top (Sodium Fluoride/Oxalate) Tube
Collection Instructions:
All Specimen Types:
- Collect and label fasting sample according to standard protocols. Each sample must be labeled with the time of draw.
- After administration of the prescribed dosage of glucose beverage, collect and label all subsequent timed samples according to standard protocols. Each sample must be labeled with the time of draw.
Serum (SST, gel-barrier):
- Gently invert tube 5 times immediately after draw.
- Allow blood to clot 30 minutes.
- Centrifuge for 10-15 minutes.
Plasma (Fluoride/Oxalate):
- Draw and gently invert tube 8 to 10 times.
- Centrifuge immediately for 10-15 minutes.
- Aliquot plasma into labeled transport tube labeled as ‘NaF plasma’ or ‘Gray Top plasma’ and cap tightly. Each aliquot sample must be labeled with the time of draw. Discard original tube.
Whole Blood (Fluoride/Oxalate):
- Draw and gently invert tube 8 to 10 times.
- Do not centrifuge
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. Serum and plasma submissions must be separated from cells. Whole blood submissions not recommended due to short stability time.
Transport: Store all samples at 2°C to 8°C after collection and ship the same day per packaging instructions included with the provided shipping box.
Stability:
Serum (SST, gel-barrier):
Ambient (15-25°C): 4 days
Refrigerated (2-8°C): 7 days
Frozen (-20°C): 28 days
Plasma (Fluoride/Oxalate):
Ambient (15-25°C): 7 days
Refrigerated (2-8°C): 7 days
Frozen (-20°C): 28 days
Whole Blood (Fluoride/Oxalate):
Ambient (15-25°C): Not acceptable
Refrigerated (2-8°C): 72 hours
Frozen (-20°C): Not acceptable
Causes for Rejection: Samples not labeled with the time of draw; samples that are grossly hemolyzed or lipemic; specimens other than acceptable sample type; improper labeling; samples not stored properly; samples older than stability limits.
Methodology: Photometric
Turn Around Time: 1 to 3 days
Reference Ranges:
| Specimen | Normal (mg/dL) | Prediabetes (mg/dL) | Diabetes (mg/dL) |
|---|---|---|---|
| Fasting Glucose | 65-99 | 100-125 | >125** |
| 2-h Glucose* | 65-139 | 140-199 | >199** |
*The test uses a glucose load containing the equivalent of 75g anhydrous glucose dissolved in water.
**Diagnosis must be confirmed by testing on a subsequent day.
Critical Value:
| Age | Critical Low mg/dL | Critical High mg/dL |
|---|---|---|
| All Ages | ≤40 | ≥500 |
Urgent Value:
| Age | Urgent High mg/dL |
|---|---|
| All Ages | 400-499 |
Clinical Significance: 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 who have had a normal glucose test.
References:
- 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.