Glucose Tolerance Test

WHAT IS GLUCOSE TOLERANCE TEST?

Glucose tolerance test, which is also called “oral tolerance test”, is defined as a test that is used to ascertain and measures the level of sugar in the blood and how the body responds to it. 

A glucose tolerance test is used to check for diabetes especially type 2. In some cases, it could be used for diagnosing gestational diabetes that develops during pregnancy. It usually involves comparing of results of your blood glucose level before and after you take a sugary substance.

REASONS FOR GLUCOSE TOLERANCE TEST

The glucose tolerance test makes it possible to be able to check abnormalities that occur in the body after the body has taken its meal often before your fasting blood glucose level goes back to normal. It is usually done to ascertain the level of impaired glucose tolerance in the body, type 2 diabetes, and gestational pregnancy.

WHAT DOES GLUCOSE TOLERANCE TEST MEASURE?

This test measures the glucose level in your body and how your body reacts to it by assessing how well it processes a large amount of sugar. It is used to test for diabetes, insulin resistance, and reactive hypoglycemia.

Types Of Glucose Test

There are two types of glucose test namely:

• Glucagon Challenge Test

This usually the short version of the glucose tolerance test. This procedure involves drinking a concentrated solution of 50g of glucose in 300ml of water with a blood sample taken after an hour. It can be done at any times of the day

• Glucose Tolerance Test

This is referred to as the longer version of the glucose test as it requires abstinence from food for a minimum of 8-12 hours depending on your medical need.

WHAT IS THE RISK ASSOCIATED WITH GLUCOSE TOLERANCE TEST?

The risk obtained in taking glucose tolerance tests is in association with dizziness obtained from the withdrawal of the blood sample in the lab. Sometimes you may experience bleeding and bruising.

WHO IS ELIGIBLE FOR GLUCOSE TOLERANCE TEST?

Your doctor will prescribe or recommend this test for you, mostly for people with type 2 diabetes, gestational diabetes in pregnant women. 

According to the American College of Obstetricians and Gynecologists, they recommend that an hour blood glucose challenge test to screen for gestational diabetes in pregnant women between 24 and 28 weeks of pregnancy that have a low risk of having gestational pregnancy. 

They could be factors that could affect the development of gestational diabetes which includes previous gestational pregnancy, a family history of diabetes, obesity, polycystic ovary syndrome, etc.

GLUCOSE TOLERANCE TEST PREPARATION

You can prepare for the glucose tolerance test by eating properly days before the test and then avoiding eating at least eight hours before the test. Most of the meals you will be advised to stay on before the period of the test will be mainly carbohydrates.

Bring along the medications that you are taking if any. Avoid drinking or smoking before the test as it could affect the result.

Let the doctor know if you have any illnesses. Your doctor will also advise you on how to fast before coming and the number of hours depending on your medical needs

GLUCOSE TOLERANCE TEST PROCEDURES

Before Procedure,

You will be expected to eat normally days before then. Alert the doctor of any medications you might be taking and if you feeling any new symptoms as this factor might influence the result. 

On the day of the test, you will be required to eat nothing for eight hours before the test is done. If you schedule for the test in the morning, you might want to overnight.

During Procedure,

During the procedure, a blood sample called a fasting sample will be taken in other to measure your fasting blood glucose level. This is used to compare other results. 

If you are being tested for type 2 diabetes, you will be asked to drink about 237 millimeters of a glucose solution containing 75 grams of sugar. After that, your blood glucose will be checked again.

If you are being tested for gestational diabetes, your doctor will check certain risk factors that could increase your risk of having gestational pregnancy and if you have a high-risk profile, you might be required to do a three-hour glucose tolerance test.  

You will need to avoid eating and drinking for some hours in other get your accurate fasting blood glucose level. You will be asked to drink about 237 millimeters of a glucose solution containing 100 grams of sugar. Then your blood glucose level will be tested again after about three hours after you have drunk the solution.

After Procedure,

After the test, your doctor would interpret the results for you and then you can go home. The results are usually given in milligrams per deciliter or millimoles per liter.

WHAT DOES THE RESULT SAY?

The normal blood glucose level is lower than 140mg/Dl. As a result, for people suspected of having type 2 diabetes, your glucose level may read 200mg/Dl or higher. 

A blood glucose level of about 140 and 199 mg/Dl shows impaired glucose level and you stand the risk of developing diabetes type 2 and also some heart diseases. 

The result suggests type 2 diabetes, then your doctor may conduct the test again another day to confirm the accuracy of the result as there could be factors that could affect the results.

If the test was conducted to check for gestational diabetes, the result will be closely examined. If the result is higher than normal after a one-hour test, then a three-hour test may be conducted and the result examined. 

If the result is higher than 190mg/dl then you will be diagnosed of having gestational diabetes. Your doctor may need to still have you redo the test another day, in other to confirm the diagnosis.

You will be asked to be careful will what you eat if you are diagnosed with having gestational diabetes throughout your pregnancy or type 2 diabetes.

WHAT ARE SIDE EFFECTS OR COMPLICATIONS FROM A GLUCOSE TOLERANCE TEST?

Normally, there are no effects that arise from undergoing a glucose tolerance test apart from the little mark on your skin where the needle was inserted to take your blood and the swelling of the vein that was used which goes down after a day or two.

FAQs

• What is the normal result for glucose tolerant tests during pregnancy?

Normally the result for glucose tolerant test that indicates the absence of gestational pregnancy is a 140mg/dl level of blood sugar.

• Why do I have to stay on carbohydrate meals mostly before the test?

You will be asked to stay on carbohydrate meals mostly before the test to enable your body to prepare for carbohydrate metabolism and as a result, producing a more accurate result when you are tested.

• What are the warnings of gestational pregnancy?

The warning signs of gestational pregnancy include sugar in the urine, increase in thirst, frequent urination, tiredness, nausea, blurred vision, vaginal, skin, and bladder infection.

• Does diet affect glucose tolerance tests?

Dieting may affect the accurate result of glucose tolerance test as it may not show clearly how the body response the s to the sugar level in the body

• Can you fail the one-hour test and pass the three-hour glucose test?

The possibility of the one glucose cause test being accurate is higher than that of a three-hour test as a one-hour glucose test may not give clear information on your body’s metabolism of sugar.