Cystic fibrosis is an inherited disease characterized by the buildup of thick, sticky mucus that can damage many of the body's organs.Most men with cystic fibrosis have congenital bilateral absence of the vas deferens (CBAVD), a condition in which the tubes that carry sperm (the vas deferens) are blocked by mucus and do not develop properly.In people with cystic fibrosis, mucus often damages the pancreas, impairing its ability to produce insulin and digestive enzymes.In people with cystic fibrosis, the body produces mucus that is abnormally thick and sticky.In adolescence or adulthood, a shortage of insulin can cause a form of diabetes known as cystic fibrosis-related diabetes mellitus (CFRDM).Adults with cystic fibrosis experience health problems affecting the respiratory, digestive, and reproductive systems.Over time, mucus buildup and infections result in permanent lung damage, including the formation of scar tissue (fibrosis) and cysts in the lungs.Most people with cystic fibrosis also have digestive problems.With improved treatments and better ways to manage the disease, many people with cystic fibrosis now live well into adulthood.