Specimen Required

Container/Tube:
Preferred: Lithium Heparin (Mint)
Acceptable: Serum gel, Tiger top, Red top
Specimen Volume: 1.0 mL

Glucose Drink Dosage: 75 grams

Collection Instructions:

Patient Preparation:

a. The patient must be fasting 8 to 14 hours prior to Glucose Tolerance Test (GTT) measures.

b. The patient is instructed to avoid smoking, drinking beverages(water is acceptable), mild or strenuous exercise prior to and during the test.

c. Advise the patient to remain at the testing site for the duration of the test procedure. Physical activities such as walking are not permissible.

d. When collecting multiple timed specimens (2hr GTT, 3hr GTT, 5hr. GTT) a fasting specimen must be collected prior to patient drinking the glucose drink.

e. Serve glucose tolerance drink chilled. Do not serve glucose drink on ice. Instruct the patient to drink the solution in no more than 5 minutes.  Patient must be observed drinking the glucose solution.

Note:  If test data are to be accurate, test conditions must be controlled rigidly. Patients should have a normal diet for three days prior to GTT. Anorexia or any other conditions precluding adequate food intake automatically invalidates the test. Inactivity for three days prior to GTT, such as bed rest, has been reported to impair glucose tolerance; thus GTT should not be performed in non-ambulatory patients. Endocrine disorders such as acromegaly, hyperthyroidism, or Cushing’s syndrome frequently are associated with abnormal glucose tolerance. Thus, dysfunction of the endocrine system should be evaluated and corrected before a GTT is performed. Certain medications may affect insulin secretion and blood glucose levels. Patients should check with their physician for instructions on the use of medications prior to GTT procedure.

Plasma gel tubes should be centrifuged within 2 hours of collection. 4 hours is acceptable.
Serum gel tubes should be fully clotted and centrifuged within 2 hours of collection. 4 hours is acceptable.
Red-top tubes should be fully clotted, centrifuged and aliquoted within 2 hours of collection.4 hours is acceptable.