Diabetes is a very common complication that develops over time in many people with cystic fibrosis (CF) . In fact, most adults living with CF have some degree of diabetes or glucose intolerance. Cystic fibrosis—related diabetes (CFRD) is a unique type of diabetes that only people with cystic fibrosis can get. CFRD is similar to, but not the same as, diabetes in people who do not have cystic fibrosis. Consequently, treatment of CFRD is not the same as treatment of other types of diabetes.
What is Diabetes?
Normally, the digestive system converts some of the food that we eat into sugar. The sugar, known as glucose, enters the bloodstream. High levels of glucose in the blood trigger the pancreas to secrete a hormone called "insulin," which helps carry the glucose from the blood to the cells of the body. In people with diabetes, this system does not function properly and the glucose remains in the blood. If left untreated, diabetes can cause permanent damage to the eyes, kidneys, heart and nervous system.
Types of Diabetes
In people who do not have cystic fibrosis, there are two types of chronic diabetes:
Type 1: This type of diabetes, which is usually diagnosed in childhood, occurs when the pancreas does not produce enough insulin, a condition known as insulin deficiency. Due to these characteristics, type 1 diabetes used to be called "insulin-dependent" or "juvenile onset diabetes." People who have type 1 diabetes must take insulin shots every day of their lives or they could develop a life-threatening condition called "ketoacidosis."
Type 2: This type of diabetes, which is usually diagnosed in adulthood, occurs when the pancreas produces enough insulin, but the body does not respond to the insulin properly, a condition known as insulin resistance. Due to these characteristics, Type 2 diabetes used to be called "noninsulin dependent" or "adult onset diabetes." People with Type 2 diabetes usually do not need to take insulin shots. Instead, they take pills that help their bodies use the insulin that they already have.
CFRD – How It’s Different and What Causes It
Diabetes in people with cystic fibrosis combines the characteristics of both type 1 and type 2 diabetes. Build up of thick secretions in the pancreas eventually damages the hormone-producing cells, causing insulin deficiency. This sounds like type 1 diabetes, but it is not quite the same thing because it does not start in childhood, but in adulthood, and is caused by damage to a pancreas that used to produce insulin normally.
In addition to insulin deficiency, people with cystic fibrosis often wind up with insulin resistance because of:
- Chronic infections
- High levels of cortisol, a hormone that the body secretes in response to stress
- Frequent exposure to corticosteroids, which are anti-inflammatory drugs sometimes used in the treatment of lung conditions that mimic the action of cortisol.
The symptoms of CFRD are the same as the symptoms for any type of diabetes:
- Excessive thirst
- Frequent urination
- Excessive fatigue
- Unexplained weight loss
The problem is that all of these symptoms mostly occur in people with cystic fibrosis, whether or not they have CFRD. This makes early detection difficult.
Since symptoms of CRFD may not be noticed in the early stages of the disease, the Cystic Fibrosis Foundation recommends routine screening for diabetes at least once a year for all patients age 14 and older. CFRD is diagnosed by blood tests that detect the levels of glucose in the blood.
CFRD is usually treated with a combination of insulin, exercise and diet. The diet for people with CFRD is different than the calorie-restricted diet typically prescribed for people with other types of diabetes. Despite their diabetes, people with CF must maintain high-calorie, high-fat diets and compensate by adjusting insulin doses. If you have CFRD, you will need to work closely with your physician and nutritionist to develop the treatment plan that works best for you.
Hardin, D., et al. 2002. “Managing Cystic Fibrosis-Related Diabetes (CFRD)”. 3rd Edition. Cystic Fibrosis Foundation. 04 October 2008