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Oral Glucose Tolerance Test (OGTT)

What Is a 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 blood work to help diagnose any problem.

Description of the Test

Blood levels can be affected by food. Therefore, the patient cannot eat for 8 hours before the test. He / she can only drink water before the test.

  1. Upon arrival, the patient may have a height and weight measurement.
  2. Your child will have an IV catheter (a small thin tube) placed in the arm. Blood is drawn through the IV catheter. Most often, this vein is in a hand or arm. Getting an IV may hurt a bit but is done quickly.
  3. The patient is then given a very sweet drink. It is important to finish this drink in five minutes.
  4. Blood is obtained and tested at three time points (for up to three hours) after finishing the drink to measure glucose and insulin levels over time.
  5. When the test is finished, the patient is given a meal of his / her choice and the IV catheter is removed.

After the Test

Test results are available from your provider two weeks after the test date.


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

Last Updated 05/2019

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To learn more, schedule an appointment, or refer a patient, contact the Division of Endocrinology. Contact Us