Cystic fibrosis-related diabetes (CFRD) is a form of diabetes unique to people with cystic fibrosis. It has some features of both Type-1 and Type-2 diabetes. As with all types of diabetes, the person’s blood glucose (blood sugar) is too high because the pancreas is not making enough insulin or, for those with CF, insulin is not being excreted.
CFRD typically develops between ages 18 and 21, with 50% of those with CF developing it by age 30. Some children show signs of impaired glucose tolerance as young as 10.1 That is why the CF Foundation recommends that screening for CFRD begin around age 10.2
Causes of cystic fibrosis-related diabetes
People with CFRD do not have diabetes because they are overweight. People with CF develop CF-related diabetes due to the long-term damage done by the thick mucus that blocks the pancreatic duct. These blockages preventing pancreatic enzymes from reaching the intestines lead to scarring, or fibrosis, of the pancreas. Once it is scarred, it makes it harder for the pancreas to secrete insulin, another of its important functions. This results in diabetes mellitus, or CF-related diabetes.
Symptoms of CF-related diabetes
Symptoms of CF-related diabetes are similar to those of Type 1 and Type 2 diabetes and include:
- Needing to urinate or drink more often
- Feeling very tired
- Losing or not gaining weight
- Unexplained decline in lung function (This only occurs in CF)
If you experience any of these symptoms, it is important to talk to your CF care team right away.
Diagnosis of CFRD
CF-related diabetes is diagnosed through an oral glucose tolerance test (OGTT). The test is performed after a person has had nothing to eat or drink for 8 to 12 hours. Blood samples are taken before and up to 2 hours after drinking a specific amount of glucose. Glucose is sugar dissolved in water.
Treatment of CFRD
People with CF-related diabetes take insulin injections. Unlike Type 2 diabetes, people with CF-related diabetes should not limit calories or lose weight. People with CF who also develop diabetes have different nutritional needs than Type 1 or Type 2 diabetics and still should eat a high-calorie, high-protein, high-fat, high-salt diet. This helps them maintain a healthy weight.
Keeping blood glucose at an average level helps the person with CF feel more energetic, maintain a healthy weight, and lowers the risks of problems caused by diabetes such as kidney disease. It also helps the person maintain better lung function and have fewer exacerbations.
People with CF who also have CFRD should see an endocrinologist, a doctor who specializes in treating diabetes.