What is a Oral Glucose Tolerance Test?

One of the most common tests for the measurement of tolerance of glucose is the Oral Glucose Tolerance Test. This test can be defined as the measurement of the body’s capability to metabolize glucose or simply put, break down glucose and clear it from the blood. The test is basically done to diagnose diabetes which could be type II diabetes, diabetes during pregnancy (gestational diabetes) or pre-diabetes.

How is the test done?

The test is done by asking the patient to drink a liquid that has a certain amount of glucose. This amount is 75 gm for normal people and 100gm for pregnant women. Blood samples are taken prior to taking the glucose mixed solution and then after every 30 minutes to 60 minutes, up to nearly five times. The test usually takes nearly 3 hours. Prior to taking the test, the patient should have been fasting for nearly 12 hours before the test.

The reliability of the oral glucose tolerance test depends on certain factors. Some conditions like an ailment (even common cold), or food (caffeine by way of coffee) and lifestyle habits (smoking) may affect the results of the test. Therefore it is important to inform the patient about these and ask him to take care of these factors prior to going in for the test.

The test is helpful in the diagnosis of high blood glucose levels if the fasting blood sugar level of the patient is normal.