Cystic Fibrosis Related Diabetes

Donal O’Shea, Jean O’Connell

Improved life expectancy in cystic fibrosis (CF) has led to an expanding population of adults with CF, now representing almost 50 % of the total CF population. This creates new challenges from long-term complications such as diabetes mellitus (DM), a condition that is present in 40 %-50 % of adults with CF. Cystic fibrosis-related diabetes (CFRD) results from a primary defect of insulin deficiency and although sharing features with type 1 (DM1) and type 2 diabetes (DM2), it is a clinically distinct condition. Progression to diabetes is associated with poorer CF clinical outcomes and increased mortality. CFRD is not associated with an increased risk of cardiovascular disease and the prevalence of microvascular complications is lower than DM1 or DM2. Rather, the primary goal of insulin therapy is the preservation of lung function and optimization of nutritional status. There is increasing evidence that appropriate screening and early intervention with insulin can reverse weight loss and improve pulmonary function. This approach may include targeting postprandial hyperglycemia not detected by standard diagnostic tests such as the oral glucose tolerance test. Further clinical research is required to guide when and how much to intervene in patients who are already dealing with the burden of one chronic illness.