Glucose, Two-hour Postprandial
Also known as: Postprandial Sugar, PP Glucose, Two-hour (After Meal)
Use
Only a minority of patients with diabetes mellitus have the classic symptoms of polyuria, polyphagia, polydipsia, and weight loss. The two-hour postprandial glucose is extensively used to establish the diagnosis of diabetes mellitus. It may be used along with FBS to follow patients with impaired glucose tolerance.
Special Instructions
Ensure the patient has consumed an adequate meal or a 75-gram glucose load two hours prior to the test, as per the physician's instructions. The meal should be completed within 15 to 20 minutes. Stressed patients, such as those undergoing surgery, infections, or using corticosteroids, should not take the test. Proper labeling of the specimen with the patient's name and collection time is required to avoid rejection.
Limitations
This test should not be conducted on stressed patients, including those experiencing surgery, infection, or corticosteroid use, as these conditions can affect glucose levels. Specimens lacking proper labeling, especially collection time, may be rejected. The minimum volume provided does not allow for repeat testing, emphasizing the need for accurate and correct sample collection.
Methodology
Automated Analyzer (Clinical Chemistry)
Biomarkers
LOINC Codes
- 1521-4
- 1521-4
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.5 mL
Container
Gel-barrier tube
Collection Instructions
Collect specimen two hours from the beginning of meal. Separate serum or plasma from cells within 45 minutes of venipuncture. Gray-top tubes only, may be submitted without centrifugation. Label tube with patient's name and collection time.
Patient Preparation
Adequate meal or 75-gram glucose load two hours before two-hour postprandial glucose, as specified by the patient's physician. Patient is allowed usual meal (breakfast or lunch). Patient must complete meal within 15 to 20 minutes.
Storage Instructions
Maintain specimen at room temperature.
Causes for Rejection
Stressed patients (surgery, infection, corticosteroids) should not have GTT; specimens not labeled with collection time.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |