Specimen Requirements

Plasma or serum is required.

Patient Preparation
1. Patient should not be receiving intravenous glucose.
2. Patient should be on at least a 150 g carbohydrate diet for 3 days prior to testing and should be off all hypoglycemic drugs, such as birth control pills, aspirin, diuretics, ethanol, and steroids.
3. Patient should not have any acute illness or other stress at the time of the test.
4. Ideally, the test should not be performed on hospitalized patients.

5. Test should begin at 7 a.m to 9 a.m. after a 8 to 12 hour fast.
6. Patient should remain quiet during test, and no food, medication, or smoking allowed.
7. If diarrhea or vomiting occurs, test is aborted and should be done another day.

Specimen Collection

Submit only 1 of the following specimens:

Plasma
1. Method of collection must remain consistent. If you start with a vein stick, continue with a vein stick. If you start with a fingerstick, continue with fingerstick.

2. Draw blood in a green-top (heparin) MICROTAINER, a grey-top (potassium oxalate/sodium fluoride) tube, or a plasma gel tube from a fasting patient.

3. Spin down and send 1 mL of heparinized or potassium oxalate/sodium fluoride plasma refrigerated. Collect specimen as follows:
A. Fasting glucose is drawn in a grey-top (potassium oxalate/sodium fluoride) tube.

B. Patient is given a 75 g dose of glucose. Pregnant patients receive 100 g dose of glucose.  Instruct patient to drink the whole amount within several minutes. Note the time when the patient has finished. All drawing times are calculated from finish time.
C. Draw a fasting, 1/2 hour, 1 hour, 2 hours, etc. specimen. Physician may order from a 2-hour up to a 6-hour tolerance.
D. Patient should remain fasting; only small amounts of water are permitted.
Note: 1. Indicate plasma on request form.

2. Label specimen with appropriate patient information, date and time, “fasting“, “1/2 hour”, “1 hour”, “2 hours”, etc., and as plasma.

Serum

1. Method of collection must remain consistent. If you start with a vein stick, continue with a vein stick. If you start with a fingerstick, continue with fingerstick.

2. Draw blood in a plain, red-top tube or a serum gel tube. Spin down and send 1 mL of serum refrigerated. Collect specimen as follows:
A. Fasting glucose is drawn in a plain, red-top tube or a serum gel tube.

B. Patient is given a 75 g dose of glucose.  Pregnant patients receive 100 g dose of glucose.  Instruct patient to drink the whole amount within several minutes. Note the time when the patient has finished. All drawing times are calculated from finish time.
C. Draw a fasting, 1/2 hour, 1 hour, 2 hours, etc. specimen. Physician may order from a 2-hour up to a 6-hour tolerance.
D. Patient should remain fasting; only small amounts of water are permitted.
Note: 1. Indicate serum on request form.

2. Label specimen with appropriate patient information, date and time, “fasting“, “1/2 hour”, “1 hour”, “2 hours”, etc., and as serum.