Cystic fibrosis-related diabetes (CFRD) is a unique type of diabetes that is common in people with CF. With early diagnosis and proper treatment, CFRD can be managed successfully
What is Cystic Fibrosis Related Diabetes?
Cystic fibrosis related diabetes (CFRD) is a unique type of diabetes that is common in people with cystic fibrosis (CF).
With early diagnosis and proper treatment, CFRD can be successfully managed. People with CF are prone to scarring in their pancreas caused by thick sticky mucus build-up. The scarring stops the pancreas from producing enough insulin, which causes CFRD. It is similar to both Diabetes Type 1 and 2, but not the same.
People with CFRD can become insulin deficient (like people with type 1 diabetes), but can also build a resistance to insulin (a feature of type 2 diabetes). It’s recommended that people with CF are screened for diabetes regularly.
You might be asked to monitor your blood glucose level (BGL) for a day or weeks, which involves checking and recording your BGL before breakfast (known as a fasting BGL) and two hours after meals.
Normally when you eat, the rise of glucose in your blood triggers the pancreas to release insulin.
Insulin is the hormone produced in the pancreas that moves the glucose out of your bloodstream into your cells, allowing the cells to do the work needed to keep your body healthy.
A normal BGL for someone without diabetes is between 3.3 and 6 mmols/L, and rarely rise above 9 mmols/L (millimoles per litre).
When you have diabetes, your body either doesn’t create enough insulin or builds a resistance to insulin, which results in high BGL.
Understanding how food, exercise, and insulin affect the BGL is vital to keeping your CFRD under control. Uncontrolled CFRD can lead to weight loss and more frequent chest infections. Like most complications, early detection and treatment are the key to staying as healthy as possible.
CFRD can be permanent because of the decline in natural insulin production. CFRD is not caused by the high fat, high energy diet recommended for most people with CF.
But CFRD can also be temporary and caused by:
- Steroid-induced – when you are on oral steroids you may be treated for CFRD
- Pregnancy-induced – there is a higher chance of developing diabetes when you are pregnant whether you have CF or not
- Infections can also cause temporary insulin resistance
Testing for CFRD
The best test for CFRD is called the oral glucose tolerance test (OGTT).
The OGTT is usually done in the morning after an eight-hour fast. After a baseline blood test for blood glucose and insulin levels, you will be given a sugary drink. Your blood will then be tested 30 minutes, one hour and two hours later.
Another test used is the glycated haemoglobin (HbA1c) test, a blood test which shows average level of glucose in the blood over the past three months.
For anyone with any form of diabetes, life is a balancing act – balancing blood sugar levels and/or insulin levels. The same is true of CFRD.
Keeping your BGL at normal to near-normal levels means the body is better able to function, you will have more energy and feel better.
Managing CFRD involves a combination of insulin and diet. Insulin is injected into the body so sugars and proteins can move from the blood into the body’s cells. This process allows your body to create energy, build muscle, and store fat. Your CF health team will work out the right type of insulin for you and help you with a diet plan.
Diet for people with CFRD still needs to be the same high-calorie diet that anyone with CF needs. This is different to people with Type 1 or Type 2 Diabetes. The only difference is that people with CFRD need to track or count the foods that affect their blood sugar levels the most.
Physical activity like exercise is good for lung function and can help your body’s response to insulin. People with CFRD are encouraged to exercise regularly and check in with their CF health team to make sure their exercise regime is still working.
Monitoring blood glucose levels
Blood glucose level (BGL) is also known as the blood sugar level (BSL).
Checking your BGL is a quick test you can do yourself by pricking your finger and inserting the blood into a portable glucose meter. Some machines let you download the results making it easy to keep a track of them over time. If yours does make sure it’s set up with the right date and time.
It’s best to monitor and record your BGL three to four times a day:
- Before breakfast (fasting)
- Before taking your insulin with lunch
- Before taking your insulin with dinner
- Before going to bed
It’s very important to eat after taking insulin, otherwise you are at high risk of a hypoglycaemic attack.
Other times you should check your BGL:
- When you feel like you are having a hypoglycaemic attack (see below for explanation)
- Before driving a vehicle
- Before and after exercising
- Two hours after a meal or starting an overnight feed
|Aims for your blood glucose level (BGL) mmols/L|
|Before meals||4.5 – 7.0|
|Two hours after meals||Less than 10.0 ideally 8.0 – 9.0|
|At bedtime||5.5 – 8.0|
|Before exercise||Between 6.0 – 14.9|
|Before driving||Between 5.0 – 10.0|
Hypoglycaemia (hypo) is when your BGL drops too low – less than 4mmols.
- Weakness and trembling
- Pins and needles around the lips
- Blurred or double vision
If you feel any of these symptoms, you need to act quickly and eat fast acting carbohydrates (high GI food) like jelly beans (five to seven), high glucose tablets (three to four) or soft drink (half a cup). Always carry one of these with you just in case.
After you have eaten the high GI food, wait 10 minutes and check your BGL. If it is still NOT above 4mmol/L, have some more high GI food.
Try and eat a meal within half an hour, but it’s not meal time have a low GI food to prevent any more hypos. Try a high energy supplemental drink, a glass of milk, a piece of fruit or a packet of potato chips.
Causes of and ways to prevent hypoglycaemia
|Causes of hypos||Ways to prevent hypos|
|Not eating enough carbohydrate at the meal (or skipping a meal)||Have regular meals and mid-meals with enough carbohydrates. Avoid going too long without eating try to eat every 2-4 hours.|
|Too much or unexpected activity / exercise||Eat extra carbohydrate snacks or drinks when doing more than your usual exercise. Avoid giving insulin in the parts of your body that you will work out.|
|Taking too much insulin, especially if you then miss a meal or snack||Ensure you take your correct dose of insulin for the number of carbohydrate exchanges.|
|Drinking excess alcohol||If you drink alcohol, do so in moderation and make sure that you eat some carbohydrate foods while you are having a drink. Remember that there is always a risk of going low several hours after you have stopped drinking.|
Your CF health team can help you with your insulin dosage, and keeping a record of your BGL over time will help them help you.
Hyperglycaemia is a high BGL and can develop over many hours, days or years.
Symptoms of hyperglycaemia include:
- Feeling excessively thirsty
- Frequently passing large volumes of urine
- Infections (e.g. thrush, cystitis, wound infections)
- Feeling tired
- Blurred vision
- Weight loss
Causes of hyperglycaemia include:
- Not enough or the right type of insulin
- Too much carbohydrate food at once
- Some medicines such as oral steroids
You might not experience any symptoms of hyperglycaemia until your blood sugar levels reach extreme levels. This is why it’s important to keep a track of it.
Driving and CFRD
Having CFRD doesn’t stop you from being able to drive, but you must report it.
In Australia if you are prescribed insulin and hold a drivers licence you have an obligation to report your diabetes to your states’ roads authority. They will give you a medical form to be filled out by your endocrinologist.
Test and be safe
Hypos can happen at any time and could happen when you are behind the wheel, putting you and others on the road at risk.
So before you get in the driver’s seat:
- Check your blood glucose level is between 5.0 – 10.0 mmols/L
- If your BGL is 5.0mmols/L or under have a snack particularly if you’ve had insulin in the two hours beforehand
- Carry high GI food in the car
- Never inject insulin and drive off without eating – even if your BGL is high
If driving and you feel a hypo coming on, STOP the car or bike immediately and treat the hypo. Don’t keep driving to the next petrol station/shop
Those few minutes may mean the difference between arriving safely and having an accident, injuring yourself, your passengers and other road users.
It is recommended you speak to your specialist team regarding more specific CFRD issues and questions.