Oral Glucose Tolerance Test (OGTT)

The oral glucose tolerance test (OGTT) measures the body's use of glucose (sugar). Glucose is the body's main source of energy. Insulin (produced by the pancreas) helps the body use glucose.

Your healthcare provider may order this test along with other laboratory work to help diagnose any problem.

Blood laboratory levels can be affected by food. Therefore, the patient cannot eat before the test. He / she man drink only water eight to 12 hours before the test.

On the day of the test, the patient drinks a sweet beverage. Blood is obtained and tested before and at 30-minute intervals (for up to three hours) after drinking it to measure glucose (and insulin, if required) levels over time.

  1. Upon arrival, the patient may have a height and weight measurement.
  2. A small needle will be used to take blood from a vein. The blood is tested. Most often, this vein is in a hand or arm. Some patients complain of pain when the needle is placed. Others describe a prick or stinging sensation. A skin-numbing cream can sometimes be used to eliminate pain, if planned in advance.
  3. The patient is then given a very sweet drink. It is important to finish this drink in five minutes.
  4. Blood is tested at 30-minute intervals (for up to three hours) after finishing the drink.
  5. When the test is finished, the patient is given a meal of his / her choice.

Test results are available from your physician two weeks after the test date. The patient should not feel any side effects from this test except for mild discomfort or stiffness at the blood draw site.

The patient should dress comfortably. You may bring an item of comfort such as a doll, blanket or stuffed animal.

Last Updated 11/2013