About Pancreatic Exocrine Insufficiency Pancreatic exocrine insufficiency (PEI) is a condition, not a disease. The condition is commonly associated with diseases such as pancreatitis or cystic fibrosis, in which patients have a shortage of digestive enzymes necessary to break down food and digest the fats, proteins and carbohydrates contained in food.  This leads to nutrient malabsorption and is associated with weight loss, diarrhea, abdominal tenderness, loss of appetite/feeling of fulness, and fatty/foul-smelling stools (steatorrhea).