Patients with hereditary cardiovascular and diabetic conditions are generally advised to take the test once every 6 months or annually. Patients with a personal medical history of such conditions are advised to take this test frequently, as per the discretion of the doctor.
Procedure for the Glucose Tolerance Test
The procedures for the shorter and the detailed version of the glucose test vary to some extent. The procedures have been explained below:
Glucose Tolerance Test:
The GTT can be performed orally by inserting a BC-shielded IV catheter or with multiple phlebotomy draws.
For the oral glucose tolerance test, the fasting blood sample will be collected for testing at a laboratory. The exact timing at which the blood sample is taken will be recorded. Next, a glucose solution will be given, determined by your weight but not more than 75 gms. This has to be consumed within a maximum of 5 minutes. This will be repeated two or three more times, with an interval of 30 to 60 minutes each. The time intervals and the number of times the glucose solution is taken vary between laboratories.
In case a BC-shielded IV catheter is being used, the line is usually lushed with a heparin solution or saline after each sample is collected. This is done to ensure the patency of the line. After all the blood samples have been collected, they are sent to the laboratory for microscopic analysis.
Glucose Challenge Test:
For the glucose challenge test or the shorter version of the test, the concentrated glucose solution of about 50 grams mixed in 250 to 300 ml of water is consumed. The blood sample is then collected after an hour and sent to the laboratory for close analysis under a microscope. This test can be conducted at any time of the day.