What is Cystic Fibrosis-related Diabetes?


Note: This article is part of our library of resources for Forms of Diabetes.

What is Cystic Fibrosis?

Cystic Fibrosis (CF) is a progressive genetic disease that causes a buildup of thick, excessive mucus in the lungs, pancreas, liver and kidney. The buildup of mucus in the lungs leads to chronic infections and difficulty breathing; the buildup of mucus in the pancreas leads to scarring and the blocking of enzymes that aid in food digestion and nutrient breakdown.

What is Cystic Fibrosis-related Diabetes (CFRD)?

People who have cystic fibrosis develop excessive mucus, which in turn can scar the pancreas. If scarring occurs, the pancreas stops producing normal amounts of insulin, causing the person to become “insulin deficient” like someone with type 1 diabetes.

Sometimes, a person with CFRD may not be able to absorb the insulin like someone with type 2 diabetes, making them, (like type 2), “insulin resistant.” The later may occur when the person is sick, on steroid medication or when pregnant (Cystic Fibrosis Foundation).

What are symptoms of Cystic Fibrosis-related Diabetes (CFRD)?

Symptoms are similar to that of type 1 diabetes; however, they can be similar to cystic fibrosis symptoms that go unnoticed. Only testing for diabetes can properly diagnosis CFRD. These are the common signs of CFRD:

  • Extreme thirst
  • Frequent urination
  • Extreme weight loss
  • Fatigue
  • Decline in lung function
  • High blood sugars (hyperglycemia)

Screenings and Diagnosis for CFRD

It is recommended that children ages 10 and older who have been diagnosed with cystic fibrosis are screened annually for CFRD with an oral glucose tolerance test (OGTT). The OGTT will be given after an eight-hour fast, and is the best way to screen for CFRD. Other tests for CFRD include fasting blood glucose tests, casual blood glucose tests and testing hemoglobin A1c (HbA1c).

The following guidelines have been established for the diagnosis of CFRD:

  1. Two-hour OGTT glucose ≥ 11.1 mmol/L200 mg/dl
  2. Fasting blood glucose  ≥ 7.0 mmol/L126 mg/dl
  3. Hemoglobin A1c ≥ 6.5% (note: HbA1c is often low in CF and a value < 6.5% does not rule out CFRD)


Treatment for CFRD is similar to treatment for type 1 and type 2 diabetes. The goal is to keep blood sugar at normal or close-to-normal levels. CFRD can be well managed by consistently monitoring blood glucose levels, treatment with insulin, maintaining your normal diet and staying active.

Insulin is injected into your body and helps absorb the carbohydrates you eat to convert them into energy. There are different types of insulin, each with different mechanisms of action. People with CFRD should work with their doctors to determine the amount of insulin to take as well as how many carbohydrates they should be eating.

Regular exercise is important for people with CFRD to improve lung function and the body’s response to insulin. When taking insulin and exercising it is important to monitor blood glucose levels and be aware of the signs of low blood sugar (hypoglycemia).

People with CFRD should maintain the same high-calorie, high-protein, high-fat, high-salt diet necessary for people with cystic fibrosis to maintain a healthy body weight.

WRITTEN BY BT1 Editorial Team, POSTED 11/18/16, UPDATED 04/18/23

This piece was authored collaboratively by the Beyond Type 1 Editorial Team.