What is a Glucose Tolerance Test and Why Do You Need One?

Glucose Tolerance Test
Spread the love

Are you experiencing symptoms of diabetes? If the answer is yes, then you may need to undergo a glucose tolerance test.

This diagnostic test helps healthcare professionals evaluate how well your body processes sugar, an important factor in maintaining overall health and wellness. But what exactly is a glucose tolerance test and why do you need one?

Keep reading to find out. 

What is a glucose tolerance test?

Typically a glucose tolerance test or GTT is used to diagnose diabetes. GTT helps to measure the body’s ability to utilize glucose, or blood sugar.

Usually, the GTT is done in two steps. The first step includes ingestion of 75 gms of anhydrous glucose (which makes the solution sweet) dissolved in water. This is followed by a test of blood sugar levels after two hours of having the sugary drink the blood sugar levels are measured. 

Generally, the normal GTT result is less than 140 milligrams per deciliter (mg/dl). However, if your blood glucose level is higher than 140 mg/dl, you may have diabetes.

Generally,  OGTT (Oral Glucose Tolerance Test) is recommended for people who are:

  • Over the age of 45 or
  • At risk of developing diabetes, such as being overweight or having a family history of the disease.

What is the normal glucose tolerance test result?

A GTT helps in measuring the body’s response to sugar (glucose). Usually the GTT is done after an overnight fast. During the test,  you will undergo a blood test to check your fasting blood sugar level. 

GTT is a blood test that helps to establish an understanding of  how well your body is able to utilize blood glucose.

What is the procedure of a glucose tolerance test?

To undergo a GTT you need to fast overnight. Once fasting blood is collected you are given a sugary solution to drink which is basically a glucose rich liquid. After drinking this solution your blood sugar is tested at intervals of an hour or 2 hours. This can be extended to 3-5 hours.

Generally GTT is not painful. However, some people may find it uncomfortable to drink a lot of sweet tasting solution for the test. Also it might be uncomfortable for some to stay still for two hours for the GTT. 

Your lab technician will guide you throughout the test.

How does a glucose tolerance test work?

A GTT is a diagnostic tool used to determine how well your body is able to process sugar. The test is usually administered after fasting for at least 8 hours, and involves drinking a sugary solution, then having your blood sugar levels checked periodically over the next 2 hours.

A normal response to the test would be for your blood sugar levels to rise, then level off or decline slightly after an hour or so. If your blood sugar levels continue to rise after 2 hours, it may indicate that you have diabetes.

Can you drink water during a glucose tolerance test?

Yes, you can drink water during a glucose tolerance test. In fact, it is important to stay hydrated during the test in order to prevent false results. Drink small sips of water throughout the test and avoid drinking large amounts of water all at once.

No more stress while managing diabetes

Don’t struggle alone & get the expert care you deserve

Invalid number
Invalid Email Id
A Smiling man with folded hands

What are the side effects of the glucose tolerance test?

It is uncommon to experience any side effects during GTT. However a few people may experience:

  • Dizziness, 
  • Sweating, 
  • Nausea, and 
  • Vomiting. 

If you experience any of these symptoms during the test, please contact your doctor at the earliest.


According to the World Health organization (WHO), over 77 million Indians who are above 18 years have diabetes (Type 2) and  nearly 25 million have prediabetes. 

As they say ‘Prevention is better than cure’ – Fitterfly urges all readers of this blog to get a GTT done if they are experiencing diabetes symptoms or have a family history of diabetes. It will greatly help you and your loved ones to take faster remedial measures.  

In case you already have been diagnosed with diabetes and are finding it difficult to manage your blood sugar levels – do not worry. We are here to help you. Our trusted and scientifically proven diabetes control program – Fitterfly Diabetes Care Program can help you to manage your blood glucose levels efficiently.

Our dieticians and industry experts at Fitterfly can help you with a personalized diet plan that will focus on your condition. They will also guide you completely, on exercises and stress management which are critical aspects while managing diabetes.

If you have any more questions about the Glucose tolerance test and diabetes, please feel free to contact us.

- By Fitterfly Health-Team
No more stress while managing diabetes

Don’t struggle alone & get the expert care you deserve

Invalid number
Invalid Email Id
A Smiling man with folded hands