Gestational Glucose Tolerance Diagnostic Test (Three-hour, ACOG Recommendations)
Also known as: Glucose Tolerance, Gestational Diabetes (Fasting, One-hour, Two-hour, and Three-hour)
Use
Diagnose gestational diabetes
Special Instructions
Patients must adhere to a specific diet and fasting protocol before the test: an unrestricted diet of at least 150 grams of carbohydrates for three days prior, and fasting for at least 8 hours but no more than 14 hours before the test. Discontinuation of nonessential glucose-altering medications is advised three days before testing. Patients should remain seated and avoid smoking during the test.
Limitations
The test may not be suitable for patients with known diabetes mellitus or those under physiological stress such as surgery or infection. Accurate results require strict adherence to fasting and preparation protocols. Incorrect specimen labeling with collection time intervals can lead to test rejection.
Methodology
Automated Analyzer (Clinical Chemistry)
Biomarkers
LOINC Codes
- 50586-7
- 1558-6
- 1501-6
- 1514-9
- 1530-5
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL serum each tube
Minimum Volume
0.5 mL serum each tube
Container
Gel-barrier tubes (4)
Collection Instructions
Draw fasting blood sugar before administering 100-gram glucose, then draw blood at one, two, and three hours. Separate serum from cells within 45 minutes of venipuncture. Label each tube with patient's name and collection time interval (i.e., fasting, one-hour, two-hour, and three-hour).
Patient Preparation
Eat a diet of 150+ grams of carbohydrate for three days prior. Fast for at least 8 hours before the test.
Storage Instructions
Maintain specimen at room temperature.
Causes for Rejection
Frozen gray-top tube; stressed patient; specimens not labeled with collection time intervals.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |