Oral Glucose Tolerance Test (OGTT)
OGTT, one of the diagnostic tests for type 2 diabetes, is different because it checks how the body is metabolizing glucose. Additionally, the oral glucose tolerance test takes the most time to administer. This is because you need to stay in the clinic or hospital for at least 2 hours to complete the screening.
What happens during the test?
For this test, you need to fast for 8 to 12 hours. Hence, like FBS, OGTT is best done in the morning.
- In the clinic, the healthcare worker will draw your blood and measure your fasting blood sugar level.
- After that, they will give you a glucose drink (around 75 grams), which tastes like a “very sweet soda.”
- After drinking the liquid glucose, the healthcare practitioner will periodically measure your blood sugar at 1, 2, or 3-hour mark. This means that they’ll draw a blood sample a few times within 2 to 3 hours.
How do they diagnose type 2 diabetes using OGTT?
A fasting blood sugar level of 60 to 100 mg/dl is normal. After the 1-hour mark, a result of less than 200mg/dl is also normal. What the doctors use to diagnose diabetes is the blood sugar level at the 2 hour-mark:
- A level of less than 140mg/dl is normal.
- If the result is between 140 and 199 mg/dl, it means that the person has impaired glucose tolerance or prediabetes.
- Finally, a blood sugar level of 200 mg/dl or more indicates diabetes.
What else should I know?
Besides fasting before the test, you also cannot eat anything during the test. If you have medications that you need to take, talk to your doctor about what to do. Many reports say that OGTT detects diabetes with more accuracy than FBS. However, it’s more expensive and requires more time.
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