What is an Oral Glucose Tolerance Test (OGTT)?

An oral glucose tolerance test (OGTT) checks how your child’s body handles glucose (sugar). If the body does not handle sugar the right way, it can lead to prediabetes or diabetes. If your child has 1 of these conditions, they may need medicine or other treatments. Problems with blood sugar can also make cystic fibrosis (CF) symptoms worse.

What is Diabetes?

Diabetes is a condition that affects how the body uses food for energy. Insulin is a hormone made by the pancreas. It helps move glucose (sugar) from the blood stream into the body’s cells to be used for energy. When there is not enough insulin, too much sugar stays in the blood.

In people with cystic fibrosis (CF), the mucus that normally protects the nose, throat, mouth, and lungs becomes thick and sticky. This thick mucus can damage and block the pancreas, making it harder for the body to produce enough insulin. Over time, this can lead to cystic fibrosis-related diabetes (CFRD).

How Do I Prepare My Child for the Test?

• Three days before the test, your child should eat 3 to 4 servings of carbohydrates (carbs) at each meal. This helps their body prepare for the test. Foods high in carbs include pizza, bread, cereal, rice, crackers, fruit, juice, milk, yogurt, beans, pasta, potatoes, and corn.
• Sweet foods and snack foods are also high in carbs and often fats too. These foods may include soda, juice drinks, syrup, honey, cake, cookies, donuts, pudding, candy, and chips.
• Your child cannot eat or drink anything except water for 10 hours before the test.
• If your child eats or drinks anything other than water, the test will be cancelled.

How is the Test Done?

The oral glucose tolerance test includes 3 blood tests.

1. Go to the Laboratory on the 1st floor of the Craig Yubuki Tower for the first blood test.
2. After the first blood test, go to the CF clinic, where your child may be given a sweet drink.
3. One hour after drinking the sweet drink, the second blood test will be done in the lab.
4. Two hours after drinking the sweet drink, the final blood test will be done in the lab.

How Often Does my Child Need to Have this Test Done?

Children and teens with cystic fibrosis should have this test once a year, starting at 10 years of age. If it is difficult to schedule the blood test during a clinic visit, the test may be done at a lab closer to your home. Ask the provider for lab orders.

Attention: This test cannot be done if your child is sick, as illness can affect the test results.

• If your child is sick, call the CF clinic at 414-266-6730 to cancel the test.
• You should still plan to bring your child to their CF clinic visit, unless you are told otherwise.