What is the Connection Between Cystic Fibrosis and Diabetes?

Cystic fibrosis is an inherited condition that affects many systems of the body. The disease causes problems with pancreatic function, which over time can lead to diabetes. Diagnosis and treatment of the diabetes seen in cystic fibrosis patients is similar to diabetes rooted in other causes. The mainstay in treatment of cystic fibrosis related diabetes is subcutaneous insulin.

Cystic fibrosis is a genetic disease caused by a mutation in a gene encoding for a chloride channel. In normal people, the chloride channel is widely distributed throughout the body, but in patients affected by cystic fibrosis there are no working copies of this chloride channel. As a result, they develop a number of medical complications affecting the respiratory tract, nasal sinuses, skeleton, reproductive tract, biliary system, and the pancreas.

The pancreas problems caused by cystic fibrosis are what link it to diabetes. Due to its lack of normal chloride channels, the pancreas of a patient with cystic fibrosis cannot produce the proper digestive enzymes. Poor functioning of the pancreas over time leads to recurrent bouts of pancreatitis, as well as diminishing production of pancreatic enzymes and hormones. This eventually leads to a loss of the endocrine function of the pancreas, which includes its role as a secretor of insulin.

A patient with cystic fibrosis whose pancreas does not have the ability to produce insulin is considered to have cystic fibrosis related diabetes (CFRD). Approximately 25 percent of patients with cystic fibrosis have cystic fibrosis and diabetes by age 20, and the incidence of CFRD increases with age. With advances in other aspects of treating cystic fibrosis, patients with this disease are living longer. As a result, the number of people with both cystic fibrosis and diabetes is increasing.

Symptoms of cystic fibrosis related diabetes can include high blood glucose levels, increased thirst, increased urination, loss of peripheral sensation, and decreased vision. The condition can be diagnosed by checking fasting blood glucose levels, by performing an oral glucose tolerance test, or by checking the glycated hemoglobin level. Some doctors taking care of adult cystic fibrosis patients regularly screen for CFRD due to its high prevalence.

Cystic fibrosis related diabetes is often treated with subcutaneous insulin. In some ways, CFRD is similar to type 1 diabetes mellitus, which is a pathologic condition in which patients have an autoimmune destruction of the pancreatic cells that make insulin. Just as patients with type 1 diabetes mellitus require exogenous insulin to survive, patients with cystic fibrosis and diabetes also require insulin injections.