CFTR and diabetes mellitus: Furthermore, up to 30% of European adults with CF and 50% of adults in the United States with CF will experience a CF-specific type of diabetes referred to as CF-related diabetes (CFRD), a condition that arises due to pancreatic damage over time from a lack of functional cystic fibrosis transmembrane conductance regulator (CFTR) activity in the pancreas [17,24,25].