- Below 140 milligrams per deciliter - normal
- 140 to 199 milligrams per deciliter - impaired glucose tolerance or prediabetes
- Above 199 milligrams per deciliter - diabetes
September 17, 2016
Information on the Glucose Tolerance Test
I have only been exposed to the glucose tolerance test one time. That was back in the early 1990s. All I know was that I passed the test for what the level for diabetes during that time. Then, I did not know what the level was for being a person with diabetes. I knew what diabetes was and what it could do for people that did not manage their diabetes.
I was lucky because both my mother's parents had type 2 diabetes and my grandfather took some time when I was young to try to explain what type 2 diabetes did to people's body if they did not take care of their diabetes. He and my grandmother did not have any problems that they showed me even though my grandfather used a cane when he went out side of the house.
I know that during holidays when the family gathered there, there was plenty of food for everyone, but grandpa told me he ate sparingly and did not eat bread and I remember him doing this.
Back to the Glucose Tolerance Test or GTT or OGTT (oral) and there are other variations. This is not used as frequently by doctors today and some will not use it. They prefer the HbA1c test and rely almost exclusively on this. Yes, they use a fasting blood glucose test or a plasma glucose test to confirm diabetes, but they seldom use the GTT.
Before taking the test, the patient is asked not to eat for 8-12 hours. A sample of blood will be taken before the test begins. This fasting sample will be used to provide a comparison for the test results.
The individual will then be asked to drink a sugary drink containing a known amount of glucose (most are 75 grams of glucose) and water. The exact timing may vary, but another blood sample may be taken every 30 to 60 minutes for a total of 2 hours.
Here is what the different blood glucose levels may indicate under today's rules:
If the test results do show diabetes, the doctor may choose to repeat the test on another day or use another test to confirm the diagnosis.
Various factors can affect the accuracy of the glucose tolerance test. For the test to give reliable results, the person must be in good health and not have any other illnesses. The person should be relatively active and not be taking any medicines that could affect their blood glucose.
Diabetes is a dangerous disease. According to the Diabetes Research Institute, it affects more than 380 million people worldwide and takes more lives than AIDS and breast cancer combined. It claims the life of 1 American every 3 minutes. It is also the leading cause of blindness, kidney failure, amputations, heart failure, and stroke.
There is currently no cure for diabetes. Early detection and immediate treatment is key to controlling the disease.