Glucose Tolerance Test Lab Test

GTT

What is GTT?

GTT short for Glucose Tolerance Test is a test designed to assess the body response to glucose. In GTT, the patient is given a glucose solution and blood samples are drawn afterword at intervals to measure how well the body cells are able to absorb glucose. There are several variations to the glucose tolerance test used in different conditions but, the most common one of them is the Oral glucose tolerance test or OGTT.

The OGTT is mainly used in the diagnosis of gestational diabetes. For OGTT the patient is required to fast for 8 hours and then a fasting plasma glucose is tested, after that oral glucose solution is given. After that blood samples can be drawn up to 4 times at different intervals to measure the blood glucose. A OGTT is usually performed in the morning as glucose levels usually fall by afternoon.

OGTT used to be the gold standard in the diagnosis of diabetes type 2 but, is now being replaced with other GTT methodology. The GTT is primarily used for the diagnosis of diabetes, insulin resistance, impaired beta cell function, carbohydrate metabolism disorder and also reactive hypoglycaemia and acromegaly.  

Who is given Glucose Tolerance Test (GTT)?

The GTT is usually given to pregnant women during 24th and 28th week of pregnancy. This test is also given to pregnant who has diabetes symptoms or have the risk of developing diabetes prior to the pregnancy.

Besides that the GTT is also given to other patients who are experiencing symptoms of varied diseases that can cause high glucose levels in the blood stream or restrict the proper absorption of glucose by the body cells.

What are the preparations needed for GTT?

GTT is an elaborate blood test, that requires frequent testing and as the special requirements need for GTT are as follows;

  • Have a normal diet like any other day. 
  • Inform the doctor about the varied prescription drugs you are taking, as certain drugs like corticosteroids, diuretics and anti- depressants can cause false results.
  • Fasting is required for 8 to 10 hours prior to the test and only water is allowed during this period.
  • You might want to avoid using the washroom prior to testing as urine samples might be needed
  •  On the morning of the test do not smoke or have coffee or caffeine based product.
  • The GTT is not to be done on a sick person

Glucose Tolerance Test Procedure

The GTT procedure is as follows;

  • At first a zero -time or baseline blood sample is drawn.
  • Then the patient is given a specific dose of glucose solution to drink
  • After that the blood samples are drawn at regular intervals to measure the blood sugar levels and also insulin levels in certain cases. The blood sampling can be done as requested by the doctor and could involve up to 6 hours of testing. 

GTT side effects

There is a slight risk attach with Glucose tolerance test which are as follows;

People with high levels of sugar have the following side effect in response to drinking the glucose solution, like;

  • Nausea
  • Stomach discomfort
  • Diarrhoea
  • Constipation

Risks attached to drawing out blood samples include the following;

  • Swelling and redness at the puncture side
  • Haematoma
  • Fever
  • Dizziness
  • Infection at the puncture site

GTT normal value

The GTT normal value is lower than 140 mg/dL and if the blood glucose level is between 140 and 199 mg/dL then it is a strong indication of prediabetes. 

The OGTT normal range for fasting results is between 100 – 125 mg/dL for prediabetes, 126 mg/dL or greater for diabetes and greater than 92 mg/dL for gestational diabetes.

The OGTT normal range for after 2 hour test results is between 140 – 199 mg/dL for pre diabetes, 200 mg/dL or greater for diabetes and greater than 153 mg/dL for gestational diabetes. 

GTT test result interpretation

For Gestational diabetes no further test is required and proper medication and treatment can start. In case of diabetes, further testing is advised to confirm the diagnosis. And in pre diabetes doctors start the treatment with medication and dietary changes along with lifestyle changes.

How can we help?

The GTT and OGTT are a long procedure and can take up to 6 hours of testing and could be really tiring. So, to counter that we offer GT Test at home so you can relax within the comfort of your home. Our certified healthcare professional would oversee the test at regular intervals as part of the protocol and follow standard procedure.  

So if you need GTT or OGTT don’t stress yourself out at dull clinics and hospitals rather take the test at the comfort of your home with our highly trusted at home healthcare services.   

References

  1. https://labtestsonline.org/tests/glucose-tests
  2. https://www.mayoclinic.org/tests-procedures/glucose-tolerance-test/about/pac-20394296
  3. https://medlineplus.gov/ency/article/003466.htm

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