17. Cystic Fibrosis related Diabetes (CFrD)
Cystic fibrosis related diabetes (CFRD) is a form of diabetes that happens in people who have a condition called Cystic Fibrosis.
Cystic Fibrosis (CF) is an inherited chronic disease that affects the lungs and digestive system. CF affects about 500 children and adults in New Zealand. A defective gene and its protein product cause the body to produce unusually thick, sticky mucus that can clog the lungs and cause life-threatening lung infections. The mucus can obstruct the pancreas which stops natural enzymes from helping the body break down and absorb food, and affects the ability of the pancreas to produce insulin.
In people with CF, it is this thick, sticky mucus that may cause scarring of the pancreas which stops the pancreas from producing enough insulin. Some people with CFRD may also not respond to insulin in the right way.
Insulin is a hormone produced by the pancreas, and helps the glucose to get from the blood into the cells of the body to be used for energy. Glucose comes from food that contains carbohydrates (see module on diabetes and food).
If there is not enough insulin the glucose cannot get into the cells and the body cannot make the energy it needs to function. Lack of insulin in children with CF can lead to a decrease in lung function, weight loss and overall well-being.
The common signs and symptoms of diabetes are:
Passing urine frequently (bedwetting is common)
Very thirsty and drinking lots
Decreased concentration at school
Poor healing (chronic infections such as thrush)
However, in CFRD children the first signs may be a decrease in pulmonary function (tests that measure how well the lungs work) and weight loss.
Treatment of CFRD
Children and adolescents who have developed CFRD usually need insulin to help keep their blood glucose levels as close to target range as possible (4-7mmol/L). Blood glucose levels in target range allow the body to gain or maintain weight, improve lung function, so that children feel better and have more energy. Maintaining glucose levels in target range also lowers the risk of problems caused by diabetes.
The diabetes team will work alongside the CF team to help families manage this condition. Most children and adolescents with CFRD will need to be seen regularly by the diabetes team in addition to the CF team.
Children with CF require a high calorie, high protein, high salt and high fat diet to maintain a healthy body weight. This should not change with the diagnosis of CFRD. However, it is generally best to avoid sugary drinks and some types of lollies. You will be given individualised advice from the CF dietitian about managing your child's nutrition in CFRD.
Insulin is not available in tablet form. It must be injected in the layer of subcutaneous fat under the skin. Children with CFRD may require one or more injections per day. Families of children with CFRD will receive education and support from the Paediatric Diabetes Team which will include teaching on how to administer insulin. A prescription for the insulin, syringes or needles, blood glucose meter and other supplies you require will be provided. Some supplies such as food to treat hypoglycaemia will need to be purchased.
Monitoring blood glucose levels
Children with CFRD are eligible to receive a blood glucose meter kit on prescription. You will be shown how to use the blood glucose meter and will be given a prescription for blood glucose strips.
The diabetes team will discuss how often and when your child needs to check their blood glucose levels. Testing more frequently will need to be done at the following times:
During fasting for a procedure
When there are signs or symptoms of hypoglycaemia
When your child is sick
If your child needs treatment with steroid medication
If your child starts tube feeding
If your child has an organ transplant
Before and after major surgery
Sometimes Continuous Glucose Monitoring (CGM) is helpful in children with CFRD, to work out what type of insulin regimen is going to be most effective. This is done using a sensor that sits just under the skin, and a recorder which measures and records glucose levels every 5 minutes. The sensor is worn for 7 days and the blood glucose data collected is analysed by the diabetes team. This information will help you and the diabetes team understand how food, exercise, stress and medication affect your child's blood glucose levels and to adjust insulin doses.
Hypoglycaemia (low blood glucose levels)
(see module on hypoglycaemia)
Treating CFRD with insulin can sometimes cause low blood glucose levels. Blood glucose levels less than 4mmol/L are termed hypoglycaemia or 'hypos'.
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If you have read through the information above, and you feel confident that you understand this topic, print off and fill in the evaluation form below (you might need to ask someone to print this off for you) and return to the nurse on your ward. If you have any questions, note them down on this form and your diabetes nurse specialist will discuss them with you.
Cystic Fibrosis related diabetes: Evaluation
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