75 gram, fasting, 5-hour, non-gestational glucose tolerance
Test Mnemonic
GTNG5
CPT Codes
- 82951 - QTY (1)
- 82952 - QTY (3)
Performing Laboratory
Cleveland Clinic Laboratories
Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 1 mL | Plasma | Potassium oxalate/sodium fluoride (Gray) | Centrifuge and refrigerate. | Aliquot into CCL aliquot tube |
Minimum Specimen Requirements
| Volume | Type | Container | Collect Temperature | Transport Temperature | Special Instructions |
|---|---|---|---|---|---|
| 0.3 mL |
Stability
| Environmental Condition | Description |
|---|---|
| Ambient | 24 hours |
| Refrigerated | After removed from cells: 72 hours |
| Frozen | Unacceptable |
Days Performed
Sun - Sat
Turnaround Time
8 hours
Special Info
Patient should be fasting at least 8 hours prior to the test. Collect a fasting specimen, then administer 75 grams of Dextrose within 5 minutes. Collect specimens at 1,2,3,4 and 5 hours post glucose load. Indicate collection time on each specimen.
Clinical Info
Evaluation of disorders of glucose metabolism. American Diabetes Association guidelines state a diabetes mellitus diagnosis is preliminarily made when the fasting plasma glucose meets or exceeds 126 mg/dL and/or the 2 hr glucose tolerance meets or exceeds 200 mg/dL. In the absence of unequivocal hyperglycemia, results should be confirmed with repeat testing. Patients are at increased risk for diabetes mellitus (prediabetes) when the fasting glucose is 100 to 125 mg/dL or the 2 hr glucose tolerance result is 140 to 199 mg/dL. Diagnostic cutoffs for the other time points are not established, and should be clinically determined.