What is Oral Glucose Tolerance Test?
The oral glucose tolerance test (OGTT), also known as the glucose tolerance test, is a lab test to how your the body’s ability to metabolize glucose, or clear it out of the bloodstream. In this procedure the The patient is asked to take a glucose drink and their blood glucose level is measured before and at intervals after the sugary drink is taken. The test can be used to diagnose diabetes, gestational diabetes or prediabetes.
The test is a more substantial indicator of diabetes than finger prick testing
Why OGTT is Done?
According to webmd.com the Oral Glucose Tolerance Test is done to:
For those who taking the test to diagnose diabetes or prediabetes, you must need first to prepare before performing the diagnostic test:
After the preparation, on the day of testing, the following steps will be done:
The Blood Test
The health professional taking a sample of your blood will:
The test is a more substantial indicator of diabetes than finger prick testing
Why OGTT is Done?
According to webmd.com the Oral Glucose Tolerance Test is done to:
- Check pregnant women for gestational diabetes. You have an increased chance of developing gestational diabetes if you:
- Have had gestational diabetes during a previous pregnancy.
- Have previously given birth to a baby who weighed more than 9 lb (4.1 kg).
- Are younger than age 25 and were overweight before getting pregnant.
- Diagnose prediabetes.
- Diagnose Insulin resistance, and
- Reactive hypoglycemia
How to Prepare the Test?
For those who taking the test to diagnose diabetes or prediabetes, you must need first to prepare before performing the diagnostic test:
- You must eat a balanced diet that contains at least 150 grams (g) of carbohydrate per day for 3 days before the test. Fruits, breads, cereals, grains, rice, crackers, and starchy vegetables such as potatoes, beans, and corn are good sources of carbohydrate.
- Fasting at least 8 to 12 hours before your first blood sample is taken. Do not eat, drink, smoke, or exercise strenuously during the fasting.
- Must tell your doctor about all prescription and nonprescription medicines you are taking, because it will affect the test results. You may be instructed to stop taking certain medicines before the test.
How is Done?
After the preparation, on the day of testing, the following steps will be done:
- A blood sample will be collected when you arrive. This is your first blood taken to measure your blood sugar (glucose) level before the test.
- The next stage is to take a very sweet tasting, glucose drink. It is best to drink the liquid quickly. For the standard glucose tolerance test, you will drink 75 grams or 100 grams. Pregnant women drink 75 grams of glucose.
- Further blood samples will then be taken either at regular intervals of say 30 or 60 minutes or a single test after 2 hours. The test could take up to 3 hours.Since activity can interfere with test results, you will be asked to sit quietly during the entire test. Do not eat during the test. You may drink only water during this time.
The health professional taking a sample of your blood will:
- Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
- Clean the needle site with alcohol.
- Put the needle into the vein. More than one needle stick may be needed.
- Attach a tube to the needle to fill it with blood.
- Remove the band from your arm when enough blood is collected.
- Apply a gauze pad or cotton ball over the needle site as the needle is removed.
- Apply pressure to the site and then a bandage.
What Should the Test Result be?
For people without diabetes:
- Fasting value (before the test): under 6 mmol/L
- At 2 hours: under 7.8 mmol/L
- Fasting value (before the test): under 6.0 to 7.0 mmol/L
- At 2 hours: under 7.9 to 11.0 mmol/L
For diabetic levels
- Fasting value (before the test): under 7.0 mmol/L
- At 2 hours: over 11.0 mmol/L
What do these OGT Test Results mean?
If you fall in the range within the impaired glucose tolerance, you will likely be advised to make lifestyle changes. In some cases, blood glucose lowering medication may be advised.
If you fall within the diabetic range, it is quite likely that blood glucose medication will be prescribed to help your body keep your blood glucose levels down.
National Institutes of Health (NIH) stated, that the OGTT it is better able to diagnose high blood glucose after a glucose challenge than the fasting blood glucose test. A doctor may recommend it if he or she suspects diabetes in cases where a patient’s fasting blood glucose level is normal. However, the test is more time-consuming and complicated than the fasting blood glucose test.
If you fall in the range within the impaired glucose tolerance, you will likely be advised to make lifestyle changes. In some cases, blood glucose lowering medication may be advised.
If you fall within the diabetic range, it is quite likely that blood glucose medication will be prescribed to help your body keep your blood glucose levels down.
National Institutes of Health (NIH) stated, that the OGTT it is better able to diagnose high blood glucose after a glucose challenge than the fasting blood glucose test. A doctor may recommend it if he or she suspects diabetes in cases where a patient’s fasting blood glucose level is normal. However, the test is more time-consuming and complicated than the fasting blood glucose test.
Source & References:
- Glucose Tolerance Test - diabetes.co.uk Retrieved last February 26, 2013
- Oral Glucose Tolerance Test - Webmd.com. Retrieved last February 26, 2013
- Glucose Tolerance Test - nlm.nih.gov . Retrieved last February 27, 2013
- Image source: http://www.diabetesinfo.org.au/webdata/images/Glucose%20Tolerance%20Test.jpg. Retrieved last February 26, 2013
