Oral Glucose Tolerance Test Explained

The Oral Glucose Tolerance Test is a tool used to diagnose diabetes or gestational diabetes. The test takes at least 4 hours after taking a fasting reading. You will be given a very very sweet drink loaded with sugar. At each hour of the test, your blood will be drawn to see how your body is able or unable to handle the sugar load.

Before having this blood sugar testing, you should eat your normal diet for many days in a row beforehand.

The night before the testing, do not drink or eat anything except water 8 hours so you're fasting. If you are taking medications that might alter your blood sugar testing results, you need to discuss this with your health care professional.

The drink that you will be given may make you have a slight unsettled stomach afterwords. The blood testing itself is not really painful if you have a technician that knows what they are doing.

Your results will be measured and determined whether they are normal or abnormal. It is based on the following scale:

1. Fasting should be under 100 mg.

2. Levels should be less than 200 mg after one hour of the drink

3. Two hours after the sweet drink your blood sugar should be under 140. If it is over that level, you are considered at least pre-diabetic. With a reading of 200 or greater, it is considered as diabetes.

For women that are pregnant, this scale is slightly different for normal and abnormal ranges. The scale in diagnosing gestational diabetes will go as follows:

1. Fasting should be under 95 mg

2. One hour- less than 180 mg

3. Two hours-less than 155 mg

4. Three hours-less than 140 mg

Sometimes a laboratory will vary their normal ranges from other labs. But the consensus for both gestational and other people is that the fasting values should remain under 100. If your results are higher or way above the scale here, it most likely means that you have diabetes. Some doctors will do a fasting re-check a couple of times besides the oral glucose tolerance test to really see the whole picture of blood sugar metabolizing.

Other conditions that may cause high blood sugars may not be diabetes, but other problems as well such as Cushing's Syndrome. Cushing's Syndrome is a hormonal disease that displays symptoms of acne, abnormal body hair growth, and other problems which relate to the endocrine system.

In any event, this test is mainly used for the purpose of in-depth diabetes screening. Above normal results will help your doctor make an informed decision on treatment plans.