What is a glucose tolerance test?

The glucose tolerance test (OGTT) is a glucose load test that can detect the body's ability to regulate blood sugar and determine whether the subject has abnormal glucose regulation and diabetes. It is the gold standard for diagnosing diabetes.

1. The specific method is as follows:

Starting from 7 to 9 am, after the subjects have fasted (8 to 10 hours) and have their venous blood drawn, 75 grams of anhydrous glucose powder is dissolved in 200 to 300 ml of water and drunk within 5 to 10 minutes. The timing starts from the first sip of the sugar solution, and venous blood is drawn and sent for testing 1 hour, 2 hours, and 3 hours after taking the sugar, as shown in the figure below.

2. Notes:

(1) The timing starts from the first sip of sugar water.

(2) During the entire trial, the subjects cannot eat, but can drink a small amount of water. They cannot drink tea or coffee, smoke, or engage in strenuous exercise, but they do not need to stay in bed.

(3) During the first 3 days of this trial, the daily carbohydrate intake should be no less than 150 g.

(4) Stop taking any drugs that may affect the test, such as contraceptives, corticosteroids, diuretics, or phenytoin sodium, for 3 to 7 days before the test.

(5) The specimen should be sent for testing as soon as possible to avoid glycolysis causing a decrease in blood glucose concentration, which would affect the test results.

(6) In clinical practice, 82.5 g of hydrated glucose is equivalent to 75 g of anhydrous glucose.

(7) For children, 1.75 g of glucose per kilogram of body weight should be used, and the total amount of anhydrous glucose should not exceed 75 g.