Oral Glucose Tolerance Test
The OGTT is a two-hour test that checks your blood glucose levels before and two hours after you drink a special sweet drink. It tells the doctor how your body processes sugar.
- Diabetes is diagnosed at two-hour blood glucose of greater than or equal to 200 mg/dl
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Oral Glucose Tolerance Test |
| Normal |
| 200 mg/dl or higher |
Will The Glucose Tests Make Me Feel Sick
Some moms-to-be feel nauseated after drinking the glucose solution, and a few even throw up. It may help to eat something a few hours before the screening test. If you vomit soon after you’ve gotten the drink down, you’ll have to come back on another day and repeat the test.
It’s actually more common for women to feel sick during the three-hour glucose tolerance test, because the solution for that test is twice as sweet or contains twice as much liquid as the one for the screening test, and you have to drink it after fasting.
What Is A 2
The 2-hour glucose tolerance test is used to determine how well a persons body processes glucose. Glucose is the sugar the body uses for energy. This test is designed to measure how glucose is processed over a period of time by measuring fasting glucose levels as well as levels several hours after ingesting a glucose solution. This type of testing is typically done to aid in the diagnosis of type 2 diabetes.
A glucose tolerance test is typically ordered when someone is believed to be at risk for diabetes. For a more thorough test which includes measurements for 4 separate blood draws, customers may order a 3-hour glucose tolerance test.
Turnaround for the 2-hour glucose tolerance test is typically 1-2 business days.
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What Do These Ogt Test Results Mean
If you are within the impaired glucose tolerance range, you will likely be advised to make lifestyle changes. In some cases, blood glucose lowering medication may be advised.
If you fall within the diabetic range, it is quite likely that blood glucose medication will be prescribed to help your body keep your blood glucose levels down.
Tests For Gestational Diabetes
Gestational diabetes is diagnosed using blood tests. Youll probably be tested between 24 and 28 weeks of pregnancy. If your risk is higher for getting gestational diabetes , your doctor may test you earlier. Blood sugar thats higher than normal early in your pregnancy may indicate you have type 1 or type 2 diabetes rather than gestational diabetes.
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A 2 Hour Versus The 3 Hour 100 G Glucose Tolerance Test For Diagnosing Gestational Diabetes Mellitus
Abstract AIM: To determine how the omission of the third hour glucose measurement of the 100 g oral glucose tolerance test affects the diagnosis of gestational diabetes mellitus . METHODS: Retrospective chart review of 876 women delivered in a tertiary care hospital in Israel during a three-year period, who underwent a 100 g 3 hour oral GTT following an abnormal 50 g glucose screen. GDM was diagnosed according to the “criterion standard” accepted in the Fourth International Workshop Conference on GDM. The results of the 100 g 3 hour oral GTT were then retrospectively re-evaluated by omission of the third hour plasma glucose measurement from the “criterion standard”. RESULTS: GDM was diagnosed in 28.4% of the study. patients, while the omission of the third hour glucose measurement resulted in a 26.4% diagnosis of GDM. The perinatal data of the 18-omitted cases suggests that their exclusion from the GDM group would not have altered substantially the perinatal outcome of the study cohort. CONCLUSIONS: A 100 g 2 hour oral GTT is a simple and economic alternative to the 100 g 3 hour oral GTT.Continue reading > >
How The Test Is Performed
The most common glucose tolerance test is the oral glucose tolerance test .
Before the test begins, a sample of blood will be taken.
You will then be asked to drink a liquid containing a certain amount of glucose . Your blood will be taken again every 30 to 60 minutes after you drink the solution.
The test may take up to 3 hours.
A similar test is the intravenous glucose tolerance test . It is rarely used, and is never used to diagnose diabetes. In one version of the IGTT, glucose is injected into your vein for 3 minutes. Blood insulin levels are measured before the injection, and again at 1 and 3 minutes after the injection. The timing may vary. This IGTT is almost always used for research purposes only.
A similar test is used in the diagnosis of growth hormone excess when both glucose and growth hormone are measured after the glucose drink is consumed.
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What Abnormal Results Mean
A glucose level that is higher than normal may mean you have pre-diabetes or diabetes:
- A 2-hour value between 140 and 200 mg/dL is called impaired glucose tolerance. Your provider may call this pre-diabetes. It means you are at increased risk of developing diabetes over time.
- Any glucose level of 200 mg/dL or higher is used to diagnose diabetes.
Serious stress to the body, such as from trauma, stroke, heart attack, or surgery, can raise your blood glucose level. Vigorous exercise can lower your blood glucose level.
Some medicines can raise or lower your blood glucose level. Before having the test, tell your provider about any medicines you are taking.
Oral Glucose Tolerance Test Risks
The oral glucose tolerance test is safe. While you will need to go to a healthcare facility or providers office, its usually an outpatient test .
You do need to have a few blood samples taken, but they do not take long and do not usually lead to any problems .
There are very few side effects or risks if youre doing the oral glucose tolerance test. Some people have a hard time drinking the oral glucose solution. They may feel nauseated and even vomit. If this happens, the test may not be able to be completed that day.
People are watched closely during the test to make sure that they are OK. If they get low blood sugar , they will be treated right away.
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What Your Results Mean
Your provider will get the results of your oral glucose tolerance test within two to three days. Your test results will include reference ranges with high and low numeric values.
Any result that’s between the high and low values is considered normal. Results that are outside of the reference range can be abnormally high or abnormally low .
Two-hour oral glucose tolerance test results for adults or children are:
- Normal: Below 140 mg/dL
- Prediabetes or IGT: 140 and 199 mg/dL
- Diabetes : 200 mg/dL and above
If your blood glucose value is over 200 mg/dL, your provider will have you do the test again or use another test to confirm a diabetes diagnosis. If both tests are positive, the diagnosis is definitive.
Three-hour oral glucose tolerance test results are interpreted differently. For this, a preliminary diagnosis is made based on one or more high glucose values during one or more of the four blood draws. Abnormal values need to be confirmed by having you do the test again.
The normal reference ranges for a three-hour oral glucose tolerance test are:
- Normal in a fasted state: Less than 95 mg/dL
- Normal after one hour: Less than 180 mg/dL
- Normal after two hours: Less than 155 mg/dL
- Normal after three hours: Less than 140 mg/dL
If any of the values are high, the test is repeated in four weeks. After the second test, if two or more values are high, then gestational diabetes is definitively diagnosed.
What Are The Preparations Needed For Gtt
GTT is an elaborate blood test, that requires frequent testing and as the special requirements need for GTT are as follows
- Have a normal diet like any other day.
- Inform the doctor about the varied prescription drugs you are taking, as certain drugs like corticosteroids, diuretics and anti- depressants can cause false results.
- Fasting is required for 8 to 10 hours prior to the test and only water is allowed during this period.
- You might want to avoid using the washroom prior to testing as urine samples might be needed
- On the morning of the test do not smoke or have coffee or caffeine based product.
- The GTT is not to be done on a sick person
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How To Prepare 1 Hour Test
Glucose Tolerance 2 Hour Test 75g
Glucose Tolerance, 2 hour test, 75g This test is recommended and only available for NON-PREGNANT patients. The patient must be fasting for this test. A fasting glucose specimen will be drawn. The patient is given a 75 gram oral glucose load . Blood is drawn two hours later. Glucose tolerance 2 hr Test Glucose | 2 hr, GlucoseTolerance |Glucose| O9221 | GTT | OGTT|178 Submit only one of the following specimens: Container/Tube: Mint Green Top Collection Instructions: Centrifuge within 1hour Container/Tube: Gold Top Collection Instructions: Allow specimen to clotfor 30 minutes and centrifuge within 2hour Diagnosis determined by interpretive criteria This test is recommended and only available for NON-PREGNANTpatients. The patient must be fasting for this test. No caloric orcaffeine intake for at least 8 hours. Do not drink , eat, smoke, chew gum, candy, cough drops, etc. for at least8 hours prior to blood tests. A fasting glucose specimen will be drawn. The patient* is given a 75 gram oral glucose load. For safety and accuracy of testing, patients are encouraged tohave Oral Glucose Tolerance Tests performed at one of ourOutpatient Service Centers. GlucoCrushTM, the glucola drink used in SpectrumHealth Grand Rapids Laboratory does not contain gluten. *Pediatric patients under 95 lbs: Use thefollowing calculation to determine the amount of glucola to beadministered 2.4 x Body weight in lbs = mL of100g Glucola to administerContinue reading > >
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How Do I Get Ready
To get an accurate result on the OGTT, eat about 150 grams of carbohydrates each day for 3 days before the test. Don’t eat or drink anything except water after about 10 oâclock the night before.
You don’t need to do any special prep before the pregnancy glucose challenge test. You can eat in the morning. Just avoid foods with a lot of sugar, such as doughnuts or orange juice.
Oral Glucose Tolerance Test: Uses And Results
The oral glucose tolerance test measures how well the body can break down and use sugar as well as clear it from the bloodstream. Its also called a glucose tolerance test and is safe for adults and children.
For the test, you drink a syrupy solution after not eating for a while . A few blood samples are taken to see how your body is handling the sugar in the drink.
The oral glucose tolerance test can diagnose type 1 diabetes, type 2 diabetes, pregnancy-related diabetes , and high blood sugar levels that put someone at risk for type 2 diabetes .
This article will go over why the oral glucose tolerance test is used, what to expect if you have to have it done, and what your results mean.
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What Is The Glucose Tolerance Test
The glucose tolerance test is also called the oral glucose tolerance test or the three-hour glucose test. The GTT determines for sure whether you have gestational diabetes. Usually, you’ll be asked to take this test if you’ve received a positive result on the glucose screening test.
In many ways, the GTT is similar to the screening test, but it takes longer and requires multiple blood draws.
Cost And Health Insurance
The oral glucose tolerance test might be covered in part or in full by your health insurance.
Prior authorization is usually not required for an oral glucose tolerance test, but it’s still a good idea to ask your insurance carrier how much the copay or coinsurance for the test will be.
If you do not have health insurance, shop around for the best price. Independent labs tend to have lower costs than healthcare providers’ offices or hospitals.
You can also ask if the facility has a patient assistance program that offers a tiered price structure or monthly payment plans.
It can be helpful to find out this information before you need it, especially if there’s a chance you’ll need to have more tests in the future.
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What Is The Glucose Challenge Screening Test
No preparation is required prior to the test. During the test, the mother is asked to drink a sweet liquid and then will have blood drawn one hour from having the drink, as blood glucose levels normally peak within one hour. No fasting is required prior to this test.
The test evaluates how your body processes sugar. A high level in your blood may indicate your body is not processing sugar effectively . If the results of this screen are positive, the woman may have the Glucose Tolerance Test performed. It is important to note that not all women who test positive for the Glucose Challenge Screening test are found to have diabetes upon further diagnosis.
Risks And Side Effects
Most people do not experience any side effects from glucose testing, and serious complications are rare.
As it involves fasting and blood testing, the glucose tolerance test might cause nausea, light-headedness, shortness of breath, and sweating in some people.
The doctor uses a needle to draw the blood, so the injection may cause moderate pain for some.
More serious but less common risks include:
- excessive bleeding
The glucose tolerance test is not the only way to diagnose diabetes. Doctors use other tests to diagnose and monitor the condition.
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What If I Have Gestational Diabetes
GD is increasingly common, with about 7% of women having the condition. If you are found to have GD, you will work closely with your health care provider to keep your blood glucose levels in a healthy range. This involves choosing a healthy diet, gaining the recommended weight during your pregnancy, getting exercise, and if needed, taking insulin or pills to lower your blood sugar. Your babys wellbeing will be carefully monitored by regular measurements of growth and amniotic fluid volume. If you have GD you will be offered a repeat glucose tolerance test between 6 weeks and 6 months postpartum to detect prediabetes and diabetes. You may also be offered induction between 38-40 weeks of pregnancy. Finally, it is strongly recommended that women with GD breastfeed their infants.
I Have The Results Of My Glucose Screening Test What’s The Normal Range For Blood Sugar
Different providers use different standards for determining whether your level is too high. Some will say that if your one-hour blood sugar level is 140 milligrams of glucose per deciliter of blood plasma or more, you need to have the glucose tolerance test. Others put the cutoff at 130 mg/dL to catch more women who may have gestational diabetes, even though there are likely to be more false positives this way.
If your blood glucose level for this screening is higher than 200 mg/dL, most providers will consider you diabetic and you won’t be required to take the glucose tolerance test.
But any score between 140 and 200 means that you’ll have to take the three-hour glucose tolerance test for a definite diagnosis.
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How To Prepare 3 Hour Test
If your doctor would like to see additional testing, based on your results from the 1 hour test, you may be asked to have a 3 hour OGTT. It is important to follow all of the instructions very carefully, as it will affect the results of the test.
When you arrive at the office a sample or baseline glucose test will be run and used for comparing other glucose values. You will be asked to drink a sweet liquid containing a measured amount of glucose, it is best to drink it quickly. Then blood samples will be collected at timed intervals of 1,2, and 3 hours after you drink the glucose.
Here is the best method of preparation: