Savefor later Page saved! You can go back to this later in your Diabetes and Me Close

Cystic fibrosis diabetes

Cystic fibrosis diabetes is a type of diabetes most common in people with cystic fibrosis.

Although people with cystic fibrosis can develop type 1 or type 2 diabetes, cystic fibrosis diabetes is a different condition. It is the most common type of diabetes in people with cystic fibrosis. It has features of both type 1 and type 2, but there are differences in how it develops and is treated. 

On this page, we’ll explain what causes cystic fibrosis diabetes and how to treat it. And we’ll share advice about where you can go for more information and support.  

What is cystic fibrosis? 

Cystic fibrosis is a genetic condition that some people are born with. It is usually diagnosed before you turn one, and is caused by both parents passing on a faulty CFTR gene. 

People with cystic fibrosis produce thick, sticky mucus, which can build up in the lungs, pancreas and other organs. This can lead to a range of symptoms, including breathing problems, lung infections and problems with digesting food. 

What causes cystic fibrosis diabetes?

The build-up of sticky mucus caused by cystic fibrosis can lead to inflammation and scarring of the pancreas. This can damage the cells that produce insulin and lead to high blood glucose (sugar) levels

As the pancreas can’t produce enough insulin, blood sugar levels may continue to rise. This is known as cystic fibrosis diabetes. 

Signs and symptoms of cystic fibrosis diabetes

Most cases of cystic fibrosis diabetes are diagnosed before symptoms begin to develop. That is why having diabetes screening as part of your ongoing cystic fibrosis care is so important.

Symptoms of cystic fibrosis diabetes may include: 

  • getting chest infections more often
  • weight loss
  • feeling really thirsty
  • going to the toilet a lot 
  • feeling more tired than usual. 

If you begin to experience any of these symptoms, it’s important that you contact your healthcare team straight away. Don’t wait for your next routine screening. 

If left untreated, high blood sugar levels can lead to weight loss, frequent chest infections and a worsening lung function. They can also lead to diabetes complications, which can seriously affect parts of your body including your eyes, feet and heart. 

Diagnosing cystic fibrosis diabetes

Cystic fibrosis diabetes can be diagnosed through continuous glucose monitoring (CGM) or an oral glucose tolerance test (OGTT). 

We understand that coming to terms with having the condition can feel overwhelming, especially as you’re already living with cystic fibrosis. But getting diagnosed will help you get the treatment and advice you need, so that you can find ways to manage your blood sugar levels and live well with the condition. 

Treating cystic fibrosis diabetes

There are a number of treatments available to help you manage cystic fibrosis diabetes. 


If you are diagnosed with cystic fibrosis diabetes, you will receive dietary advice from a specialist cystic fibrosis dietitian. They will be able to look at your diet and tailor their advice to you. 

Often, people with cystic fibrosis diabetes need to continue to eat their usual high-calorie, high-protein and high-fat diet. 

It’s important to recognise that this dietary advice is different to the advice usually given to people with type 1 or type 2 diabetes. This is because it may be difficult to maintain a healthy weight when you have cystic fibrosis, as you’re using up a lot of energy to fight infections or keep your lungs functioning. 

If you are on cystic fibrosis transmembrane conductance regulator (CFTR) modulators as part of your treatment for cystic fibrosis, you may experience weight gain. This means you may need to make some changes to your diet to maintain a healthy weight. 


Insulin injections are a common treatment option for people with cystic fibrosis diabetes. We’ve got more information about insulin and how it works, including tips on injecting it safely

Physical activity 

Being active has many health benefits if you have cystic fibrosis diabetes, and so you may find it useful to introduce some form of physical activity into your lifestyle. 

We’ve got more information about the benefits and types of exercise you may want to try. Your physio in your cystic fibrosis team will also be able to chat to you more about this and advise on the right exercise for you. 

Cystic fibrosis diabetes complications

Having diabetes can mean you’re at risk of developing complications, such as eye problems (retinopathy) and nerve damage (neuropathy). But there are steps you can take to prevent them. 

These include keeping your blood sugar, blood pressure and blood fats within your target range. Your healthcare team will discuss your targets with you. 

Some people with cystic fibrosis diabetes may also be eligible for a FreeStyle Libre flash glucose monitor on prescription from the NHS. If you live in England and are having insulin treatment for your condition, speak to your cystic fibrosis team for more information.  

You should also go to your annual diabetes health checks. We have lots more information about what they include. 

Where to find support 

Learning how to live with cystic fibrosis diabetes can be challenging, but we want you to know that there’s lots of support available to help you through this time. 

The Cystic Fibrosis Trust provide lots of specialised support for people with the condition through their fact sheet, website and helpline

And we’re here for you too. We’ve got information about looking after your emotional wellbeing that you might find useful. Or you can give our confidential helpline a call to talk through how you’re feeling.

Back to Top
Brand Icons/Telephonecheck - FontAwesomeicons/tickicons/uk