Oral glucose tolerance tests (OGTT): What to expect

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An oral glucose tolerance test is a method doctors use to screen for type 2 diabetes and prediabetes. These tests involve drinking a product that contains glucose and drawing blood to check how much glucose it contains.

This article will tell you what an oral glucose tolerance test is, how it works, the difference between this test and a home diabetes test, and when to see a doctor.

An oral glucose tolerance test (OGTT) tests for type 2 diabetes and insulin resistance. It informs health professionals about whether a person can metabolize sugar and carbohydrates.

An OGTT can indicate whether a person has the following conditions:

Find out more about the different types of diabetes.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) states that a doctor usually only does one OGTT to test for gestational diabetes. Healthcare professionals can use this test to test for prediabetes and type 2 diabetes. However, an OGTT is more expensive than other diabetes tests and more difficult to perform.

An OGTT requires a person to fast for at least 8 hours. Upon arrival at a health clinic, a healthcare professional will take a blood sample. The person then drinks a product containing glucose, and a healthcare professional takes another blood sample after 2 hours.

The results of an OGTT can indicate whether a person has prediabetes or diabetes. The following table shows the test results 2 hours after drinking a liquid that contains 75 grams of glucose:

Healthcare professionals will give pregnant women beverages that contain more glucose and use different levels to diagnose gestational diabetes.

There are several tests that healthcare professionals can use to diagnose diabetes.

Fasting plasma glucose test

A fasting plasma glucose test checks blood glucose levels at a single point in time. People must fast for 8 hours before they can take this test.

Random plasma glucose test

A random plasma glucose test does not require fasting. A doctor can use this test if a person has symptoms of diabetes and doctors don’t want to wait to do the screening.

A1C test

An A1C test checks the average blood sugar level over 3 months. People do not need to fast before taking this test.

However, this test is not accurate in people with anemia. A doctor may also use a different test if a person is African American or of Mediterranean or Southeast Asian descent, as those people can have the following variants of hemoglobin:

• Hemoglobin S: African Americans are more likely to have the hemoglobin variant, hemoglobin S, which can cause sickle cell anemia.
• Hemoglobin C: People of African American or South and Central American, Caribbean, or European descent are more likely to have the hemoglobin variant, hemoglobin C, which can cause hemoglobin C disease.
• Hemoglobin E: Asian Americans, especially those of Southeast Asian descent, are more likely to have the hemoglobin variant, hemoglobin E, which can cause hemoglobin E disease.

People with these hemoglobin variants may return an incorrectly high or low test result. This can result in doctors refusing treatment or offering ineffective therapies for diabetes, which in turn can lead to complications.

A person cannot have an OGTT at home. However, there are a variety of home diabetes tests available online, including:

• LetsGetChecked Diabetes Test: This finger prick test measures the percentage of glucose present in the blood. The company recommends people with diabetes or symptoms of diabetes take this test to monitor their blood sugar levels.
• EverlyWell Monitor Your Blood Sugar Levels: This finger prick test monitors a person’s blood sugar levels for the past 90 days. The company says it can help a person and their doctor evaluate the effectiveness of their diabetes treatments.
• Imaware At Home HbA1c Test Kit for Diabetes: This finger prick test also monitors people’s blood sugar levels. The company states that a person must fast for 8 hours before they can take the test.

However, there are differences between an OGTT and a home diabetes test.

Home diabetes tests allow people to monitor their blood sugar levels and indicate when to contact a doctor for a diagnosis. An OGTT can only be obtained from a doctor and can immediately indicate prediabetes or diabetes.

A person should only get an OGTT from a doctor, while a person can get a diabetes test at home anytime, anywhere. While both tests require a blood sample, home diabetes tests require less blood because it is a finger prick test.

Additionally, the results of OGTT and home diabetes tests are displayed differently. Home diabetes tests are A1C tests that present the results in an alternate way. The table below shows the results a person can get after taking an A1C test.

People taking diabetes tests at home should see a doctor after getting results that suggest they have prediabetes or diabetes. A doctor can do additional tests and advise people on how to deal with their condition.

The Centers for Disease Control and Prevention (CDC) states that a person should see a doctor if they have the following symptoms of diabetes:

• very frequent urination, especially at night
• very thirsty or hungry
• experience unintended weight loss
• blurred vision
• Feel numbness or tingling in your hands or feet
• feeling tired
• experience dry skin
• have slowly healing wounds
• get frequent infections

It is important to see a doctor as soon as possible if a person has symptoms of diabetes. Without treatment, diabetes can lead to complications such as diabetic retinopathy, nerve damage, heart attacks, and cancer.

Below are some frequently asked questions about OGTTs.

How long does a test take?

An OGTT takes about 2 hours. A person drinks a liquid that contains glucose, after which a doctor draws blood 2 hours later to see how much glucose is in the blood.

What drugs can a doctor prescribe?

If a doctor diagnoses a person with diabetes, he or she may prescribe insulin. They’ll recommend insulin for people with type 1 diabetes and some with type 2 diabetes. This medication can help control blood sugar levels.

Learn more about insulin.

Doctors can prescribe metformin for people with type 2 diabetes or gestational diabetes. This drug reduces the amount of glucose that the liver releases into the body.

Learn more about metformin.

Some people with type 2 diabetes can manage their condition by maintaining a moderate weight and eating a nutritious, balanced diet. A doctor will work with each individual to find the best treatment plan.

Learn more about dealing with diabetes.

OGTTs can indicate whether a person has prediabetes and diabetes. People have to fast before the test. The nurse will then ask you to drink a liquid that contains glucose and have a blood test to check your blood sugar.

While people cannot do OGTT at home, several home diabetes tests are available online. However, individuals should discuss their results with their doctor to get a diagnosis and discuss treatment plans.

source https://dailyhealthynews.ca/oral-glucose-tolerance-tests-ogtt-what-to-expect/