The majority of patients with CF are pancreatic insufficient due to mucus blocking the pancreatic ducts. The blockage prevents digestive enzymes, such as lipase, amylase, and trypsin, from being secreted by the pancreas into the intestines. The result, if untreated, is malnutrition and fatty stools. Pancreatic insufficiency can be confirmed by measuring decreased activity of fecal elastase. Patients are treated with oral pancreatic enzyme supplements. About half of CF patients develop diabetes as adults due to pancreatic abnormalities in insulin production and secretion.