Cystic Fibrosis Related Diabetes (CFRD)

CFRD is often treated with insulin
CFRD is often treated with insulin

Cystic fibrosis related diabetes (CFRD) refers to a form of diabetes as a direct consequence of having cystic fibrosis.

Diabetes is a common complication of cystic fibrosis with around 40-50% of adults with cystic fibrosis developing diabetes.

Note that the diet advice for people with CFRD is often notably different to the diet advice for other types of diabetes.

What is cystic fibrosis?

Cystic fibrosis is caused by a genetic mutation of the CFTR gene which causes the normal flow of salt and water through the body to be blocked.

This results in the body producing unusually thick mucus which can cause problems in the body such as raising the risk of dangerous lung infections and preventing the pancreas from working properly to digest food.

The symptoms of cystic fibrosis are usually spotted within the first year of a baby’s life and include:

  • Particularly salty-tasting skin
  • Persistent coughing
  • Shortness of breath
  • Frequent chest and lung infections
  • Poor growth or weight gain

Cystic fibrosis affects digestion and so a high calorie diet is needed to maintain a healthy weight.

Symptoms of diabetes in cystic fibrosis

The following symptoms of diabetes may be noticed in people with cystic fibrosis:

Diagnosis of diabetes in cystic fibrosis

It is important that a diagnosis of diabetes is not delayed to prevent deterioration of lung function. If you have the symptoms of diabetes, contact your health team who will be able to arrange a diagnosis.

An oral glucose tolerance test or continuous glucose monitoring may be used to diagnose CFRD.

Causes

Cystic fibrosis can cause scarring of the pancreas which can affect the organ’s ability to produce insulin.

Another contributing factor is insulin resistance which can also occur in people with cystic fibrosis. The impact of insulin resistance can be significantly increased whilst, or as a result of, taking corticosteroids to treat symptoms of cystic fibrosis.

Treatment

Treatment for cystic fibrosis related diabetes should aim to address the issue of keeping blood glucose levels under control, whilst enabling someone with CFRD to get sufficient nutrition to maintain a healthy weight.

CFRD is usually treated with insulin. Insulin helps to keep blood glucose levels under control which can to prevent health complications related to diabetes developing and helps the body to get the energy needed to keep a healthy weight.

Oral hypoglycemics (tablets) may be taken if there are sufficient difficulties in taking insulin. Regular blood glucose testing is an important part of the management of CFRD.

Insulin requirements may be higher during times when corticosteroids are taken to manage the symptoms of cystic fibrosis.

Management of diabetes in people with cystic fibrosis presents a different set of challenges to people with type 1 or type 2 diabetes and people with CFRD should be referred to a consultant with a specialism in managing patients with CFRD.

The combination of diabetes with cystic fibrosis can be a challenge and psychological support can be an important part of managing the two conditions as well as accepting your diagnosis.

Diet for cystic-fibrosis related diabetes

Cystic fibrosis means that adequate digestion of food is more difficult. As a result, people with CF need to have a high calorie diet which may require frequent snacks. Unlike other types of diabetes, people with CF related diabetes may be encouraged to have refined carbohydrates with an appropriate amount of insulin taken to compensate for the expected rise in blood sugar levels.

A higher fat content of the diet may be advised in place of some refined carbohydrates if blood glucose levels are hard to manage.

Complications

In addition to complications that can result directly from cystic fibrosis, such as osteoporosis, sinusitis and infections of the lung, people with CF related diabetes may also experience complications as a result of diabetes including:

The likelihood of developing these complications can be reduced through keeping blood glucose levels under good control.

Macrovascular complications, such as heart disease and stroke, tend to be relatively rare in people with CFRD.

Outlook

The median average for life expectancy for people with cystic fibrosis, according to the Cystic Fibrosis Trust, is currently 41 years. Around 10 years ago, life expectancy was estimated at 34 years so modern treatment has made significant improvements in recent years.

People with CFRD have had shorter life expectancies. In 2001, life expectancy for people with CFRD was 24 years, but this is likely to have significantly improved as well in recent years.