3 hour glucose test can i drink water

What is an oral glucose tolerance test (OGTT)?

An oral glucose tolerance test (OGTT) measures how well your body uses sugar (glucose). It can be used to find prediabetes and diabetes. It's done most often to screen for diabetes during pregnancy (gestational diabetes).

Why is this test done?

An OGTT may be done to:

• Check for prediabetes and diabetes.
• Check pregnant women for gestational diabetes.

How do you prepare for the test?

• Tell your doctor about all the prescription and non-prescription medicines you are taking. You may be told to stop taking certain medicines before the test.
• Do not eat, drink, smoke, or do strenuous exercise for at least 8 hours before your first blood sample is taken. (You can drink water before the test.)

How is the test done?

• A blood sample is taken when you arrive for the test. This is your fasting blood glucose value. It will be compared to other glucose values in your blood.
• You will drink a small cup of very sweet liquid that contains 50, 75, or 100 grams of glucose.
• You will have more blood tests over 1 to 3 hours.
• Since activity can affect test results, you will be asked to sit quietly during the entire test. Do not eat during the test. You may drink water during this time.

How does having an oral glucose tolerance test (OGTT) feel?

You may find it hard to drink the extremely sweet glucose liquid. Some people feel sick after drinking the glucose liquid and may vomit. Vomiting may prevent you from completing the test on that day.

When a blood sample is taken, you may feel nothing at all from the needle. Or you might feel a quick sting or pinch.

You may feel faint from having several blood samples taken in one day. But the amount of blood taken will not cause significant blood loss or anemia.

What happens after the test?

• You will probably be able to go home right away, depending on the reason for the test.
• You can go back to your usual activities right away.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse call line if you are having problems. It's also a good idea to keep a list of the medicines you take. Ask your doctor when you can expect to have your test results.

Where can you learn more?

Go to https://www.healthwise.net/patientEd

Enter D945 in the search box to learn more about "Oral Glucose Tolerance Test During Pregnancy: About This Test".

Overview

The glucose challenge test, also called the one-hour glucose tolerance test, measures your body's response to sugar (glucose). The glucose challenge test is done during pregnancy to screen for gestational diabetes — diabetes that develops during pregnancy.

The test is done in two steps. First you drink a sugary solution. One hour later, your blood sugar level is measured. The results indicate whether you might have gestational diabetes.

If the test results are outside the standard range, you might need further testing to determine the diagnosis.

Why it's done

The glucose challenge test is used to screen for gestational diabetes during pregnancy.

If you're at average risk of gestational diabetes, you'll likely be screened during your second trimester — between 24 and 28 weeks of pregnancy.

If you're at high risk of gestational diabetes, your health care provider may recommend doing the screening as early as your first prenatal visit. Risk factors may include:

• Being or having a body mass index of 30 or higher (obesity).
• A lack of physical activity.
• Gestational diabetes in an earlier pregnancy.
• Having a medical condition associated with the development of diabetes, such as metabolic syndrome or polycystic ovary syndrome.
• Diabetes in a blood relative.
• Previously delivering a baby weighing more than 9 pounds (4.1 kilograms).
• Race and ethnicity — Women who are Black, Hispanic, American Indian and Asian American have a higher risk of developing gestational diabetes.

Most women who have gestational diabetes deliver healthy babies. However, without careful management, gestational diabetes can lead to pregnancy complications such as a serious condition that causes high blood pressure and other symptoms that can threaten the lives of both mother and baby (preeclampsia). Gestational diabetes can also increase your risk of having a baby with an excessive birth weight — which might increase the risk of birth injuries or prompt a C-section delivery.

Women who've had gestational diabetes also have a higher risk of getting type 2 diabetes.

How you prepare

You do not need to fast before the glucose challenge test.

What you can expect

The glucose challenge test is done in two steps. When you arrive at your health care provider's office or the lab, you'll drink a syrupy glucose solution that contains 1.8 ounces (50 grams) of sugar.

You'll need to remain in your health care provider's office or the lab while you wait for your blood sugar level to be tested. You can't eat or drink anything other than water at this point.

One hour later, a blood sample will be taken from a vein in your arm. This blood sample will be used to measure your blood sugar level.

After the glucose challenge test, you can return to your usual activities immediately. Your health care provider will give you the test results at a later time.

Results

Results of the glucose challenge test are given in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L).

• A blood sugar level below 140 mg/dL (7.8 mmol/L) is considered standard.
• A blood sugar level of 140 mg/dL (7.8 mmol/L) to less than 190 mg/dL (10.6 mmol/L) indicates the need for a three-hour glucose tolerance test to diagnose gestational diabetes.
• A blood sugar level of 190 (10.6 mmol/L) or higher indicates gestational diabetes. Further testing might not be needed.

Some clinics or labs use a lower threshold of 130 mg/dL (7.2 mmol/L) when screening for gestational diabetes.

If you're diagnosed with gestational diabetes, you can prevent complications by carefully managing your blood glucose level throughout the rest of your pregnancy. The American College of Obstetricians and Gynecologists also recommends that women diagnosed with gestational diabetes have a two-hour glucose tolerance test 4 to 12 weeks after childbirth. This test screens for type 2 diabetes. If you have questions, talk to your health care provider.

Sept. 08, 2021

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