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What is the OGTT test? Know Everything

The OGTT test or the Oral Glucose Tolerance Test, also known as The Glucose Tolerance Test is used to diagnose diabetes mellitus or insulin resistance in your system. It can also be used to diagnose gestational diabetes in pregnant women and reactive hypoglycaemia.

Although diabetes is tested using the general finger-prick method, this test is a more reliable method of this disease. In this article, we will help you understand everything that you need to know about the OGTT test and why it is necessary to get one.

What is the OGTT test?

The Oral Glucose Tolerance Test check the blood sugar levels from your food and how well your body is handling it. It is a great way of understanding if you are at risk of getting diabetes or you already have it. This test also helps you check for diabetes during pregnancy.

The individual will be asked to drink something that has glucose in it, and their blood sugar levels will be measured before the drink and at equal intervals after the intake. This will help the doctors determine if their body has difficulty in metabolizing sugar intake.

Why is this test required?

Generally, when you eat food, the blood sugar levels in your body rise. The pancreas in your system then releases insulin, a hormone that helps to store the sugar in your cells which can later be used for energy. This is how the blood sugar goes back to normal. However, if you have type 2 diabetes, the pancreas generates insulin, but your body is not able to use it properly. The glucose accumulates in your blood which exceeds the blood sugar levels. Excess of sugar can cause severe damage to the blood vessels in your body which can lead to kidney damage, nerve damage, heart problems, diseases in the eye and much more.

To avoid such diseases and problems, people, especially pregnant women, should consider taking this test. It is also necessary to take this test if there is some history of diabetes in your family.

What to expect from this test? How is it performed?

You may have a lot of things going on in your mind before you go for this test. Here are some pointers that will help you understand what you should expect before, during and after the test This is a very old and common method of checking the level of glucose in the body. It is the most reliable oral glucose tolerance test (OGTT). Here is how this test is performed –

  • Before the test is performed, the doctor will recommend you to fast for about 8 hours. It is best to fast overnight and take the test in the morning.
  • Next, A sample of blood is drawn from the vein.
  • The doctor will ask you to drink about 75 grams of drink with glucose.
  • The doctor will take more samples of blood every 30 – 60 mins, or at even intervals after the drink.
  • The total amount of time for the test takes about 3 hours.


There are similar tests that can be conducted to measure the blood sugar levels, however, sometimes the doctors prefer this test as it is more thorough. This test is a little different during pregnancy.

What is the accurate result of this test?

If the insulin in your body works perfectly, then after food and drinks, the blood sugar level in your body should rise and then go back to normal after a while. If the blood sugar does not go back to normal, you most likely have diabetes or are on the verge of getting it. Here is what you should look for in your test result –

  •       140 mg/dL or below – normal blood sugar level
  •       Between 140 – 199 – Glucose tolerance is impaired or on the verge of diabetes
  •       200 or higher – Diabetic


However, if you are pregnant, blood sugar levels that are 140 mg/dL or higher are not normal. If so, the doctor will recommend an OGTT, you should consider taking it.

How reliable is this test?

The person getting this test must be in good health and follow all the instructions for the test results to be accurate.

The person should go about their day as normal. They should be as active as they can and avoid taking any medication that could affect the glucose level of their blood.

Following the instructions correctly would ensure accurate results.


If you are diagnosed with prediabetes, or even diabetes, following the instructions of your doctor would help you keep it in control and not blow into something dangerous. Dieting, exercise and medicines are the best way to keep diabetes in control!

Getting an OGTT test could be really healthy, especially if there is any history of diabetes in your family.

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