Glucose Tolerance Test, 3 Specimens (75g)
Quest Diagnostics
Sample type: Plasma
Requires fasting: Yes
Phlebotomy required
Details
This test is suitable for individuals showing symptoms of diabetes or for routine diabetes screening in non-pregnant adults and children.
- Glucose, 1-hour (post 75 g glucose PO)
- Glucose, 2-hour (post 75 g glucose PO)
- Glucose, Fasting
Estimated days for results: Results should be available in 2 - 5 business days after the sample is collected
Details
Glucose Tolerance Test, 3 Specimens (75g) - This test is primarily used to diagnose diabetes in children and adults who are not pregnant. For pregnant women, a different test is recommended. To ensure accurate results, patients need to fast overnight and then consume a 75g glucose solution. A fasting blood sample is taken immediately after. For children, the glucose amount is adjusted to their body weight. Diabetes may be diagnosed if fasting glucose levels are ≥126 mg/dL or if glucose levels are ≥200 mg/dL two hours after consuming the glucose.
Who should take this test?
This test is suitable for individuals showing symptoms of diabetes or for routine diabetes screening in non-pregnant adults and children.
What type of sample is required?
Three 1 mL plasma samples are needed for this test, collected in fluoride/oxalate (gray-top) tubes.
Test Resources
For more information, please consult your healthcare provider.
2–5 business days
American Diabetes Association Diagnostic Criteria for Diabetes Mellitus
Glucose Value (mg/dL)
Interpretation Fasting 1-Hr Tolerance 2- Hr Tolerance
Normal <100 Not established <140
Impaired Fasting 100-125
Impaired Tolerance 140-199
Diabetes ≥126* ≥200*
*Must be confirmed by testing on a subsequent day.
Glucose Value (mg/dL)
Interpretation Fasting 1-Hr Tolerance 2- Hr Tolerance
Normal <100 Not established <140
Impaired Fasting 100-125
Impaired Tolerance 140-199
Diabetes ≥126* ≥200*
*Must be confirmed by testing on a subsequent day.
Fasting for 8 hours before your blood draw is required.
- Fasting before a blood draw means you don't eat or drink anything except water.
- Your doctor should provide any special instructions related to fasting for your test. Always follow your doctor's instructions.
Blood Draw Options with Fullscript
Fullscript offers several convenient phlebotomy options to complete your lab testing:
Quest Diagnostics Patient Service Centers (PSC)
- Location: Visit a nearby Quest Diagnostics Patient Service Center.
- Cost: $10 sample collection fee (paid during lab order checkout).
- Scheduling: Schedule your appointment here. Appointments are recommended to reduce wait times. Walk-ins are accepted, but may experience delays. Aim to arrive 10 minutes before your appointment.
- Collection Instructions:
- Bring a valid ID.
- Bring your digital or printed requisition form, available in the Labs tab of your Fullscript account.
- Check-in: Scan the QR code from your confirmation email or follow kiosk instructions.
- More Info: Quest Diagnostics blood draw guide
Getlabs Mobile Phlebotomy
- Location: Sample collection at your home or office.
- Cost: $85 sample collection fee (paid during lab order checkout).
- Availability: Available in most locations – enter your ZIP code during checkout to confirm.
- Scheduling: Schedule your appointment here through your Fullscript account.
- Collection Instructions:
- Have your digital or printed requisition form and valid ID ready.
- Your phlebotomist will contact you by phone to coordinate arrival.
- More Info: Getlabs blood draw guide
Specimen
- Preferred Specimen(s): Three - 1 mL plasma specimens collected in fluoride/oxalate (gray-top) tubes
- Alternative: NA
- Minimum Volume: 0.5 mL
- Collection Instructions: NA
Storage and shipping instructions
- Transport Container: Fluoride/oxalate (gray-top) tube
- Transport Temperature: Room Temperature
- Specimen Stability:
- Room temperature: 7 days
- Refrigerated: 7 days
- Frozen: 28 days
- Reject Criteria:
- Unspun serum or plasma separator tube (SST or PST) • Red-top or green-top tube (serum or heparinized plasma not separated from cells) • Anticoagulants other than lithium heparin, sodium heparin or fluoride/oxalate
State restrictions:
Patient can't order this test if they are located in Hawaii, Puerto Rico, New Jersey, New York, or Rhode Island
