Glucose Tolerance Test is the full form of GTT. GTT is a measurement used to check how the body reacts to glucose after consuming a certain amount of sugar. A GTT is also called an OGTT (oral glucose tolerance test) and is generally performed during pregnancy to rule out gestational diabetes. Another variant of the test is the IGTT (intravenous glucose tolerance test). This is rarely used where glucose is injected intravenously over 2-3 minutes.
Importance of GTT
Regardless of whether an individual is diabetic or not, timely blood sugar control is necessary to understand how well our body is able to tolerate the glucose we receive from our daily diet. After a meal, blood sugar levels rise slightly, so our pancreas releases the hormone insulin, which helps metabolize this sugar and turn it into energy that can be used by our body's cells, bringing blood sugar back to normal.
When a person is diabetic, this excess sugar is not metabolized properly because our pancreas does not produce enough insulin, which is needed to break down glucose into energy. As a result, glucose begins to accumulate in the blood and damages blood vessels and other organs of the body. This increase in blood sugar is the main cause of diabetes.
Diabetes is a progressive disorder which, if not controlled, can lead to various other problems like nerve damage, heart disease, kidney failure, glaucoma, etc.
When to undergo GTT
- A doctor recommends a GTT under the following conditions:
- If the individual has high blood pressure
- In case of obesity
- If the patient suffers from hormonal problems such as hypothyroidism or polycystic ovary syndrome.
- Any family history of diabetes.
- During pregnancy, if the baby's weight on scans is higher compared to gestational weeks or any history of gestational diabetes in previous pregnancies.
GTT Side effect and Result
- Few individuals may notice stomach pain, nausea, headache, vomiting.
- A normal fasting blood sugar range should be around 70-90 mg/dL
- Postprandial blood sugar (PPBS) - 80-140 mg/dL
- While the GTT is being performed, a normal blood sugar level would be below 140 mg/dL.
- If the result is between 140-200 mg/dL, it is considered pre-diabetic.
- A patient is considered diabetic if the test result is greater than 200 mg/dL.
- The test result varies due to several factors such as activity, exertion, stress or any underlying disease.
- If the test result is normal, there is no need to worry, but if the test result indicates prediabetes, then the doctor will recommend certain lifestyle modifications to the patient. Losing weight and an active lifestyle with the possibility of a healthy diet will definitely prove to be beneficial.
- If the test result indicates diabetes, the patient is asked to undergo several additional blood tests that include FBS, PPBS, pancreatic profile, "A1C" etc. to confirm the diagnosis.