Gastroenterologists are doctors who specialize in the field of gastroenterology. Their main task is to diagnose, treat, and prevent diseases of the gastrointestinal tract, particularly stomach and intestine. There are different types of diseases that are commonly associated with gastroenterology such as irritable bowel syndrome, Crohn's disease, ulcerative colitis and diverticulitis. Other diseases include gallbladder disease, pancreatic cancer, and duodenal ulcers.