Insulin is the key that helps glucose (sugar) get into your cells. With cystic fibrosis-related diabetes (CFRD), the body doesn’t make enough insulin and sometimes lacks normal responses to it. This insulin deficiency is partly due to the scars in the pancreas caused by the thick, sticky mucus of cystic fibrosis. The insulin resistance can come and go, with causes such as high amounts of stress, an underlying infection, chronic inflammation, and use of steroids. This is why some people with cystic fibrosis only need to take insulin while they're in the hospital or sick.

People with undiagnosed CFRD often have an inability to gain or maintain weight. This is because the glucose is in the blood and not in the cells where it can be used for energy. This can lead to long-term hyperglycemia (high blood sugar) which can cause lung infections and a decrease in lung function.

Please note: Cystic fibrosis patients are also prone to hypoglycemia (low blood sugar), but this is not typically related to the development of CFRD.

Prevention and Identification of Cystic Fibrosis-Related Diabetes

Because CFRD can cause significant health complications, it's important that we understand and monitor your risk for developing this condition. In accordance with the recommendations of the Cystic Fibrosis Foundation, our team will monitor your risk in two important ways: 

1. Routine checks of your blood sugar levels in the hospital and in clinic
2. Oral glucose tolerance testing (OGTT), when A1c level is 5.8 or above

Early diagnosis and treatment will improve your overall health, your nutritional status, your lung function, and your survival. 

What is Oral Glucose Tolerance Testing?

Oral glucose tolerance testing measures your body's response to sugar. You do not need an appointment and may go to any St. Luke’s lab for the test, as long as the order has already been placed by the CF team.

What to Expect 

• The test is conducted in the morning. You’ll be asked to fast (no food or beverages, except water) for at least 8 hours beforehand. You should eat your usual diet for 3 days before the test. 
• You'll be given a sweet beverage to drink containing a lot of sugar dissolved in water. Then you’ll sit or lie quietly for 2 hours. Your blood sugar will be measured before you drink the beverage and again one and two hours later.

Please bring a snack for immediately after the 2-hour blood sugar check, as you will likely not feel very well. It's best to have someone drive you home from this test.

Diagnosis of Cystic Fibrosis-Related Diabetes

Your CF team will make a diagnosis of CFRD when:

• Your fasting blood glucose (sugar) is greater than or equal to 126 mg/dl on two separate days
• A blood glucose taken at any time of day is greater than or equal to 200 mg/dl
• Your 2-hour OGTT blood glucose is greater than or equal to 200 mg/dl

Besides the yearly screening, CFRD can also be diagnosed if you become sick, are on IV antibiotics, are taking steroids, or are pregnant. These conditions cause the body cells to become resistant to the action of insulin, not allowing it to be absorbed into a cell. This is called insulin resistance which, when combined with not enough insulin being made by the body, causes blood glucose to rise. CFRD may also be diagnosed when people with CF are on tube feedings. 

Treatment for Cystic Fibrosis-Related Diabetes

If you are diagnosed with CFRD, your treatment plan will include insulin. We will not restrict your carbohydrate intake.