Specimen:
Collect
- One Gray Top (1HR)
- One Gray Top (2HR)
- One Gray Top (FAST)
Also Acceptable:
- One SST (1HR)
- One SST (2HR)
- One SST (FAST)
Submit
- Three 4 mL (Min:1 mL) Whole blood in Gray Top. Submit Refrigerated.
Also Acceptable:
- Three 1 mL (Min:0.5 mL) Plasma . Submit Refrigerated. Submit in a Standard Transport Tube.
- Three 1 mL (Min:0.5 mL) Serum in SST. Submit Refrigerated.
Special Handling
- ADA Recommends:
1. Perform at 24-28 weeks gestation in women not previously diagnosed with overt diabetes.
2. The GTT should be performed in the morning after an overnight fast of at least 8 hours.
3. Draw fasting specimen, then give 75gm glucola. At 1 hour draw "1 HR" post sample. At 2 hour draw "2 HR" post sample. Label tubes "Fasting", "1 HR", and "2 HR".
Other alternative samples:
Green Top (Li Hep), Lavender EDTA, Pink EDTA, Red Top.
If using alternative serum or plasma separate from cells ASAP.
Serum or plasma stability: Ambient 8 hrs, RF 3 days, FZ 1 month
Rejection Criteria
- Hemolyzed specimens
- Microbially Contaminated
- Unlabled Specimens
Stability
Ambient: 1 Day(s); Refrigerated: 3 Day(s); Frozen: Unacceptable; Incubated: Unacceptable
Methodology
- Colorimetric
- Kinetic
Performed
Mon-Fri
Reported
1-3 Day(s)
CPT Codes
- 82951
Interpretive Data
Please see report for interpretive data.
Components
- 2400 - GLUCOSE, FASTING
- 2401 - GLUCOSE, 1HR
- 2402 - GLUCOSE, 2HR
Last Updated: May 19, 2025 @ 9:13 am
Disclaimer:
It is preferable to locate tests on the website and not rely on printed test information, which may soon be out of date. Updated test information can only be guaranteed by using this website.
