Oral glucose tolerance test (OGTT)

This is an automatically translated article.

Article written by MSc Nguyen Thi Muoi - Doctor of Biochemistry, Laboratory Department - Vinmec Ha Long International Hospital

Glucose tolerance test is a method of testing the use of glucose - an important energy source for the body's vital activities. As one of the tests used to diagnose diabetes and pre-diabetes, it is very effective, especially for pregnant women, to help detect gestational diabetes early.

1. What is a glucose tolerance test?

Glucose tolerance test is a method of testing the use of glucose - an important energy source for the body's vital activities. As one of the tests used to diagnose diabetes and pre-diabetes, it is very effective, especially for pregnant women, to help detect gestational diabetes early.
Glucose tolerance testing can be done by 2 methods: 1-step method (one-step strategy) or 2-step method (two-step strategy).
Method 1 is currently being performed at Vinmec International General Hospital for both pregnant and non-pregnant women (by drinking 75g of glucose mixed in water, measuring plasma glucose before and after drinking sugar water). ).

2. When is the oral glucose tolerance test used?

For non-pregnant people: when the fasting plasma glucose is between 5.5 and 6.9 mmol/L. For pregnant women: glucose tolerance testing is recommended to screen for gestational diabetes in all pregnant women (without pre-existing diabetes) and is performed between gestational ages 24-28 the week. >>> When to screen for gestational diabetes with high-risk people
Note : Do not perform glucose tolerance testing in the following people:
People who have been identified with clearly elevated blood glucose levels and have Typical symptoms of hyperglycemia or 2 fasting blood glucose samples ≥7 mmol/L. People who are chronically malnourished, people who are seriously ill, bedridden for 3 days or more.

3. How is the oral glucose tolerance test performed?

To get the best results, follow the instructions below:
A few days before the test, you should eat normally and not take glucocorticoids, diuretics, beta-blockers, estrogen. Before performing the test, it is necessary to fast for about 10-12 hours, limit vigorous exercise and absolutely do not use stimulants such as alcohol, beer, coffee, and tobacco. The best time to do the test is in the morning after you have slept and fasted overnight. During the fasting period, still drink water as usual (should only drink filtered water, boiled water to cool). When going to a medical facility for testing, you should sit down and rest for 30 minutes before doing the test.

4. The process of performing forensic tests

A venous blood sample will be taken before drinking sugar water to measure the concentration of fasting blood glucose (hereinafter referred to as 1st blood glucose).
Immediately after the 1st blood sample, take 75g of glucose (or 1.75g/kg of body weight up to 75g in children) dissolved in 250-300ml of water, drink it for 5 minutes and ask to sit or lie down 2 o'clock.
(This is important, during the 2 hour test period, if the body is not at rest, glucose consumption/metabolism will be very variable depending on the amount of energy required for physical activity. the amount of effort you exert then, so the blood glucose test results obtained at the time points in the test will not accurately reflect the “baseline” condition of your body.
Therefore, patients should be careful. arrange time for testing only, should not take advantage while waiting for blood collection to go to the doctor, move or do things that require energy); do not eat, can drink water (filtered water or cooled boiled water);
Taking blood for glucose test after drinking sugar water: will be different between pregnant women and non-pregnant women:
For pregnant women: 02 venous blood samples will be taken at 1 hour (blood glucose first time). 2) and 2h (3rd blood glucose) For non-pregnant people: 01 venous blood sample will be taken at 2h (2nd blood glucose).

5. Evaluation of results of oral glucose tolerance test

5.1 For non-pregnant people Diabetic is diagnosed when the plasma glucose concentration at 2 hours after the test is greater than 200 mg/dL (or 11.1 mmol/L) Diagnosis of pre-diabetes ( Impaired glucose tolerance: plasma glucose concentration at 2 hours from 140-199 mg/dL (or 7.8-11.1 mmol/L) 5.2 For pregnant women Diagnosis of gestational diabetes Period when there is more than 1 plasma glucose concentration as follows:
1st glucose (fasting) ≥ 5.3 mmol/L 2nd glucose (after 1 h) ≥ 10.1 mmol/L 3rd glucose (after 1 h) ≥ 8.6 mmol/L Vinmec International General Hospital provides a package of Diabetes Screening - Dyslipidemia for customers with signs of diabetes, type 2 diabetes for the purpose of diagnosing and screening the disease. Management is based on quantitative blood tests, applying oral tolerance test (for customers with doubtful fasting blood sugar results)........ From there, the doctor will draw conclusions and give recommendations. provide advice on disease prevention as well as appropriate treatment Well, science for the patient.

Please dial HOTLINE for more information or register for an appointment HERE. Download MyVinmec app to make appointments faster and to manage your bookings easily.