Specimen Requirements

This test must be scheduled in advance with the laboratory. Call the Augusta Campus at 207-626-1583 or the Waterville Campus at 207-872-1159 to schedule appointment.

Patient Preparation

1. Consult physician for specific orders.

2. Patient should discontinue medication 3 days prior to test, if possible.

3. Patient should be on at least a 150 g carbohydrate diet for 3 days prior to test.

4. Test should be performed in the morning after an overnight fast (even black coffee should be avoided) for patients that are ambulatory.

5. Patient should be instructed that smoking and mild exercise are not permitted.

6. This test should not be performed on those patients who have had an illness during the prior 2 weeks.

7. Drugs such as salicylate, diuretics, and anticonvulsants should be avoided at least 3 days prior to performance of test.

8. Patient should be instructed to stay in the unit until all specimens have been drawn.

Performance of Test

1. Draw a blood specimen for a fasting glucose. Perform a whole blood glucose on the fasting specimen. This specimen should be checked to determine if the fasting glucose level is in the safe range. Test is continued only if the whole blood specimen is <150 mg/dL. If fasting glucose is not in safe range, consent must be obtained from ordering physician to continue procedure.

2. Give patient standard glucose solution:

A. 75 g for adults

B. Refer to chart for recommended pediatric dosage.

3. Have patient remain quiet for duration of test.

4. Start timing when patient begins to drink glucose solution. Patient must consume glucose solution within 5 minutes.

5. Draw blood specimen(s) at specifically designated time intervals, fasting, 2-hours, 3-hours, 4-hours, and 5-hours.

Specimen Collection

Draw blood in a green-top (lithium heparin) tube(s). For pediatric specimen, draw blood in a green-top (lithium heparin) MICROTAINER(S)®. Spin down immediately, and send 1 mL of lithium heparin plasma refrigerated.

Note:  

1. The same source of blood (venous or capillary) should be used throughout specimen collection and the same analytical method applied to each specimen.

2. Label specimen with patient’s name (first and last), date of birth, date and time of draw, and phlebotomist’s initials.

Specimen stability:   8 hrs at room temperature

                                    3 days when refrigerated

Minimum volume:     1 mL