The glucose tolerance test is a laboratory method to check how the body breaks down (metabolizes) sugar.
Alternative NamesOral glucose tolerance test
How the test is performedThe most common glucose tolerance test is the oral glucose tolerance test (OGTT). You cannot eat or drink anything after midnight before the test. For the test, you will be asked to drink a liquid containing a certain amount of glucose. Your blood will be taken before you do this, and again every 30 to 60 minutes after you drink the solution. The test takes up to 3 hours.
The intravenous glucose tolerance test (IGTT) is rarely used. In this test, 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, although the timing may vary.
How to prepare for the testMake sure you eat normally for several days before the test.
Do not eat or drink anything for 8-10 hours before the test. You cannot eat during the test.
Ask your health care provider if you are using medications that can interfere with the test results.
How the test will feelSome people feel nauseated or sweaty after drinking the glucose for the test.
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performedGlucose is the sugar the body uses for energy. Patients with untreated diabeteshave high blood glucose levels. Glucose tolerance tests are one of the tools used to diagnose Diabetes.
Above-normal blood glucose levels can be used to diagnose type 2 diabetes or high blood glucose during pregnancy (gestational diabetes). Insulin levels may also be measured. (Insulin is the hormone produced by the pancreas that moves glucose from the bloodstream into cells.)
The oral glucose tolerance test is used to screen pregnant women for gestational diabetes between 24 and 28 weeks of pregnancy. It may also be used in cases where the disease is suspected, despite a normal fasting blood glucose level.
Normal ValuesNormal blood values for a 75-gram oral glucose tolerance test used to check for type 2 diabetes:
Normal blood values for a 50-gram oral glucose tolerance test used to screen for gestational diabetes:
Normal blood values for a 100-gram oral glucose tolerance test used to screen for gestational diabetes:
Note: mg/dL = milligrams per deciliter
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What abnormal results meanGreater than normal levels of glucose may mean you have diabetes or gestational diabetes.
However, high glucose levels may be related to another medical problem (for example, Cushing syndrome).
What the risks areVeins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
Factors that may affect the test results:
Several drugs may cause glucose intolerance, including:
Before having the test, let your health care provider know if you are taking any of these medications.
ReferencesAmerican Diabetes Association. Standards of medical care in diabetes -- 2010. Diabetes Care. 2010;33:S11-S61.
Inzucchi SE, Sherwin RS. Type 2 diabetes mellitus. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 248.
The glucose tolerance test is a laboratory method to check how the body breaks down (metabolizes) sugar.
Alternative NamesOral glucose tolerance test
How the test is performedThe most common glucose tolerance test is the oral glucose tolerance test (OGTT). You cannot eat or drink anything for at least 8 hours before the test. For the test, you will be asked to drink a liquid containing a certain amount of glucose (usualy 75 grams). Your blood will be taken before you do this, and again every 30 to 60 minutes after you drink the solution. The test takes up to 3 hours.
The intravenous glucose tolerance test (IGTT) is rarely used, and is never used to diagnose diabetes. In this test, 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. However, the timing may vary.
How to prepare for the testMake sure you eat normally for several days before the test.
Do not eat or drink anything for 8 hours before the test. You cannot eat during the test.
Ask your health care provider if any of the medicines you take can affect the test results.
How the test will feelSome people feel nauseated, sweaty, light-headed, or faint after drinking the glucose for the test. However, this is uncommon.
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performedGlucose is the sugar the body uses for energy. Patients with untreated diabeteshave high blood glucose levels. Glucose tolerance tests are one of the tools used to diagnose diabetes.
Above-normal blood glucose levels can be used to diagnose type 2 diabetes or high blood glucose during pregnancy (gestational diabetes). Insulin levels may also be measured. (Insulin is the hormone produced by the pancreas that moves glucose from the blood into cells.)
The oral glucose tolerance test is used to screen pregnant women for gestational diabetes between 24 and 28 weeks of pregnancy. It may also be used when the disease is suspected, even though the fasting blood glucose level is normal.
Normal ValuesNormal blood values for a 75-gram oral glucose tolerance test used to check for type 2 diabetes:
Normal blood values for a 50-gram oral glucose tolerance test used to screen for gestational diabetes:
Normal blood values for a 100-gram oral glucose tolerance test used to screen for gestational diabetes:
Note: mg/dL = milligrams per deciliter
The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.
What abnormal results meanHigher-than-normal levels of glucose may mean you have prediabetes, diabetes, or gestational diabetes.
However, high glucose levels may be related to another medical problem (for example, Cushing syndrome).
What the risks areVeins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
Factors that may affect the test results:
Several drugs may cause glucose intolerance, including:
Before having the test, let your health care provider know if you are taking any of these medications.
ReferencesAmerican Diabetes Association. Standards of medical care in diabetes -- 2011. Diabetes Care. 2011;33:S11-S61.
Inzucchi SE, Sherwin RS. Type 2 diabetes mellitus. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 248.
Reviewed ByReview Date: 05/22/2011
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
The standard test is a 3 hour GTT (glucose tolerance test).
To test for the amount of sugars (glucose) in the blood.
Just the presence of glucose Just the presence of glucose
Not necessarily, there is a glucose test in a BMP. This can be non-fasting or fasting.
glucose
A common test to diagnose hypoglycemia is the extended oral glucose tolerance test.
The standard test is a 3 hour GTT (glucose tolerance test).
The glucose tolerance test is a lab test to check how your body breaks down sugar.
during the third triamester
A1c
Yes
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Chemistry
When I had a glucose tolerance test during pregnancy I was told to fast from midnight the night before, I was told to only drink water and nothing else, hope that helps!
No tubes are required. This can simply be done using a "fingerstick" glucose monitor.
Glucose Tolerance Test Grey Top Tube.