Specimen Requirements

Patient Preparation:

1. Patient should eat a regular diet (at least 150 g of carbohydrates or 1,500 calories) for at least 3 days prior to testing.
2. Advise patient to fast for at least 12 hours before test, and to avoid smoking or drinking coffee prior to and during test.
3. When possible, this test should be administered in the morning, and patient should be advised to remain calm and quiet for duration of test.
4. Vomiting negates the test

Blood glucose is drawn fasting and 2 hours after 75 g of oral bolus of glucose as follows:

1. Following an overnight fast (8 - 14 hours), a fasting glucose is drawn, and processed immediately. Do NOT administer glucose beverage until fasting glucose is resulted. The glucose result must be < 200 mg/dL to proceed with the tolerance. If > 200 mg/dL, consult with physician.
2. After the fasting glucose results are evaluated, have the patient drink the 75g glucose tolerance beverage.  Ingestion should be completed within 5 minutes.  The timing starts when the patient finishes the required dose of glucose tolerance beverage.
3. Draw second specimen 2 hours after the ingestion of the glucose tolerance beverage and label specimen with correct collection time.

Note:  Contact Ridgeview Medical Center Laboratory at 952-442-2191 for special instructions on pediatric patients.

Specimen Type: Plasma or Serum

Collection Container/Tube:

Preferred: Green-top (lithium heparin) gel tube following an overnight (12-14 hours) fast

Acceptable: Plain, red-top tube or SST

Specimen Volume: 2 mL

Pediatric (minimum) volume: 0.5 mL