Diabetes Mellitus and the Colon.

OPINION STATEMENT: Diabetes mellitus (DM) can affect the structure and function of the colon promoting commonly encountered lower gastrointestinal symptoms such as constipation, diarrhea, abdominal distention, bloating, and abdominal pain. Specific colonic disorders for which adults with DM are at greater risk include chronic constipation, enteropathic diarrhea, colorectal cancer (CRC), inflammatory bowel disease, microscopic colitis, and Clostridium difficile colitis. Smooth muscle structure and function, density of the interstitial cells of Cajal, and the health and function of the autonomic and enteric nerves of the colon are all potential affected by DM. These effects can in turn lead to alterations in colon motility, visceral sensation, immune function, endothelial function, and the colonic microbiome. The evaluation and treatment for slow transit constipation as well as pelvic floor dysfunction should be considered when constipation symptoms are refractory to initial treatment measures. DM-related medications and small bowel conditions such as celiac disease and small intestinal bowel overgrowth should be considered and excluded before a diagnosis of enteropathic diarrhea is made. Given the higher risk of CRC, adults with DM should be appropriately screened and may require a longer bowel preparation to ensure an adequate evaluation.