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To view specimen requirements and codes please select your laboratory:
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Glucose Tolerance Test 2-Hour (75 gm)
Fasting, 1-Hour, 2-Hour glucose
Fasting is required
5 mL whole blood collected in a sodium floride (gray-top) tube for each determination
Draw a fasting sample first. Patient to be given 75 gm dose of glucola after fasting specimen is drawn. Draw the second sample 1 hour after the patient finishes drinking the glucola. Draw third sample 1 hour after the second draw. If patient is under 95 pounds, call the laboratory for special dosing procedure for glucola. Indicate collection time on each sample container.
Original collection tube(s) for each draw
Refrigerated (cold packs)
Room temperature: 24 hours
Refrigerated: 7 days
Frozen: 30 days
Set up: Daily; Report available: 1 day
Glucose levels may be depressed if sample is left on clot for an excessive length of time.
American Diabetes Association
|Glucose Value (mg/dL)|
|Interpretation||Fasting||1-Hr Tolerance||2- Hr Tolerance|
|*Must be confirmed by testing on a subsequent day.|
This test is used for the routine diagnosis of diabetes in children and the non-pregnant adult. For pregnant females see test "Glucose Tolerance Test, Gestational, 4 Specimens (100 g)". For appropriate interpretation of this test, the patient must fast overnight and ingest a 75 g load of glucose. Immediately after, a fasting specimen is obtained. For children, the glucose load is 1.75 g/Kg of body weight, up to 75. The diagnosis of diabetes is made if the fasting glucose is ≥126 mg/dL or if the 2-hour specimen is ≥200 mg/dL.
The Result and LOINC information listed below should not be used for electronic interface maintenance with Quest Diagnostics. Please contact the Quest Diagnostics Connectivity Help Desk for more information at 800-697-9302.NOTE: The codes listed in the table below are not orderable Test Codes.
|Result Name||LOINC Code||Component Name|
|GLU1||GLUCOSE, 1 HOUR||12646-6||Glucose^1H post XXX challenge|
|GLU2||Glucose, 2 hour||12610-2||Glucose^2H post XXX challenge|
Reference ranges are provided as general guidance only. To interpret test results use the reference range in the laboratory report.
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.
LOINC assignment is based on a combination of test attributes, including the method used by the performing laboratory. For tests not performed by Quest Diagnostics, codes are assigned by the performing laboratory.
* The tests listed by specialist are a select group of tests offered. For a complete list of Quest Diagnostics tests, please refer to our Directory of Services.