Cystic fibrosis causes a build-up of mucus that blocks the ducts in the pancreas, reducing the amount of insulin produced and stopping digestive enzymes from reaching the intestines to aid digestion. This can cause malnutrition, leading to poor growth, physical weakness and delayed puberty. Owing to difficulties digesting fat, many people with cystic fibrosis require more fatty foods and a higher daily calorie intake than those without the condition.
Medication can help compensate for the failure of the pancreas, such as digestive enzymes that most people with cystic fibrosis take with each meal to help digest food.
In older people with cystic fibrosis, insulin production can become deficient due to increasing pancreatic disease. Some people develop cystic fibrosis-related diabetes mellitus and their blood sugar levels are no longer controlled, although this is rare in children.
Common symptoms of diabetes include thirst, hunger, weight loss and an excessive need to urinate, but not everyone will show obvious symptoms.