An oral glucose tolerance test measures the body's ability to use
glucose, a type of sugar found in fruits and many other foods. (Glucose is the
main source of energy used by the body.) After not eating all night, the person
being tested drinks a special sugar solution on the morning of the test.
A blood sugar sample is taken from a vein in the person's
arm once each hour for 3 hours to see how much the blood sugar increases and
then decreases over time. The test is done in a doctor's office or
lab.
The oral glucose tolerance test can be used to diagnose prediabetes
and diabetes. It is commonly used to screen for or diagnose diabetes that
develops during pregnancy (gestational diabetes). The oral glucose tolerance
test for gestational diabetes may be slightly different from the test for
prediabetes and diabetes.
The oral glucose tolerance test for type 2 diabetes is used less
often than other blood sugar tests for type 2 diabetes because it costs more
and requires several blood samples.
