Specimen Requirements

Note:  If patient has had a previous fasting plasma glucose level of >126 mg/dL or a casual plasma glucose of >200 mg/dL, patient meets initial criteria for diagnosis of diabetes. If these values are confirmed on a subsequent day (with fasting glucose of >126 mg/dL or a casual plasma glucose of >200 mg/dL), patient is considered to have diabetes mellitus and does not need confirmation with a glucose tolerance test.

Patient Preparation

1. Patient should fast overnight (8-14 hours).

2. Patient should have had at least 3 days of unrestricted diet (with >150 g of carbohydrate per day) and unlimited physical activity.

3. Patient should remain seated, with nothing to eat, drink, or chew during test except for water if desired. Patient may not smoke.

4. It is best if patient does not take medication during test or 3 days prior. Salicylates, diuretics, and anticonvulsants decrease insulin secretion.

Performance of Test

1. Draw a fasting specimen. Label specimen as “fasting.”

2.. Administer a 100 g dose of Glucola^TM which should be consumed as quickly as possible. Note time that patient finishes Glucola^TM. To determine correct amount of Glucola^TM, refer to side of bottle. There are 10 g of glucose per ounce, therefore, give patient 10 oz.

4. If patient vomits, test must be rescheduled.

5. Draw a specimen at 1-, 2-, and 3-hours after Glucola^TM was finished. Label specimen with time of draw and as “1-, 2-, and 3-hour.”

Specimen Collection

Submit only 1 of the following specimens for each of the timed draws

Preferred:

Draw blood in a  grey-top (potassium oxalate/sodium fluoride) tube. Send whole blood.
Note:  1.  Label specimens appropriately to indicate specimen timing.

Alternate: 

Serum or plasma

Draw blood in a plain, red-top; gold-top; or speckled-top serum gel tube(s) or a green mint top (heparin) gel tube.  Spin down and send 1 mL of serum or plasma refrigerated. It is important to separate cells from serum as soon as possible..

Note:  1. Indicate serum or plasma on the specimen.
            2. Label specimen appropriately to indicate collection timing.

Specimen Stability Information

SODIUM FLORIDE TUBE STABLE FOR 3 DAYS AT ROOM TEMPERATURE