Glucose tolerance test: questions and answers

This article answers the most frequently asked questions about the glucose tolerance test (GTT), an important test for detecting glucose metabolism disorders. The FAQ format allows you to quickly navigate even without medical training.

What is a glucose tolerance test and why is it performed?

The glucose tolerance test (GTT) or glucose load test is a laboratory test that helps evaluate how the body processes glucose. It determines the effectiveness of insulin, a hormone that regulates blood sugar levels. This test allows you to detect carbohydrate metabolism disorders before clinical symptoms appear.

This is especially true in the context of the rapid increase in the number of people with prediabetes, which, according to CDC, have more than 1 in 3 adults in the US. In Ukraine, the situation is similar: thousands of people live with impaired glucose metabolism without knowing it.

Who is recommended to undergo GTT?

People with elevated fasting glucose. People with overweight, hypertension, or high cholesterol. Women in the second trimester of pregnancy. Patients with polycystic ovary syndrome or a family history of diabetes. Those with glucose in the urine or symptoms of hyperglycemia.

How is the test itself?

The patient donates blood on an empty stomach, then drinks 75 g of glucose dissolved in 200–250 ml of water. Blood is taken again after 1 and 2 hours. During the procedure, you cannot eat, smoke, or move actively.

What are the standards for results?

If glucose after 2 hours is 7.8–11.0 mmol/L, it is a sign of prediabetes. If it is more than 11.1 mmol/L, the diagnosis of diabetes is confirmed.

Do I need to prepare for the test?

Yes. For 3 days - normal diet, no diets. In the morning before the test, you can not eat, drink only water. Avoid physical exertion and stress. Inform the doctor about taking medications that may affect glucose levels.

Why is the test important for pregnant women?

In pregnant women, the glucose tolerance test can detect gestational diabetes, a glucose metabolism disorder that first appears during pregnancy. This type of diabetes can be asymptomatic, but can cause large fetuses, hypoxia, complications during childbirth, and an increased risk of diabetes in the mother and child in the future.

The pregnancy test is performed with slightly different thresholds and a separate protocol recommended by WHO.

What are the restrictions or contraindications?

The test should not be performed in acute infections, fever, after surgery or childbirth. The test is also not recommended for patients with severe gastrointestinal diseases or allergies to glucose. The results may be false if the preparation is not followed or if medications that affect sugar levels are taken.

What to do if the result is positive?

Consultation with an endocrinologist is required. The diagnosis can be clarified with the help of additional tests - HbA1c, C-peptide analysis, glucose monitoring. In prediabetes, full recovery is possible with lifestyle changes.

The glucose tolerance test is a simple but powerful tool for early diagnosis of glucose metabolism disorders. Its importance is growing with the spread of diabetes, especially among young people and pregnant women. Timely passing the test is a step towards a long, healthy life.