This review of the literature is designed to identify the state of our knowledge about the ileal, colonic and biliary damage arising in diabetes mellitus. The approach is primarily clinical with the emphasis on the major symptoms involved: diarrhea, constipation and anal sphincter incontinence. The most common symptom, found in 20% of diabetics with neurological disease, is constipation. While the peculiar features of diabetic diarrhea have been well described, there is considerable controversy over its pathogenesis. As for sphincter dysfunction, manometric examinations will already reveal the autonomic neuropathy involved in the early asymptomatic phase. There is considerable debate over the possible involvement of the gallbladder in diabetes mellitus. Some believe that the autonomic neuropathy is involved in the pathogenesis of the lithiasis and helps to mask the pain in cholecystitis as well.