Colonic dysfunction in diabetes mellitus.

Colonic myoelectrical and motor activity were measured in 12 patients with diabetes mellitus. Diabetic patients with severe constipation were compared to diabetics with mild or no constipation. Gastric emptying and peripheral nerve conduction studies were performed in all patients. Normal subjects had a rapid increase in colonic spike and motor activity (P < 0.001) within the first 30-min postprandial period. Diabetic patients with mild constipation had a postprandial increase in colonic motility; however, the response was delayed to 60-90 min after eating. Diabetic patients with severe constipation had no postprandial increase in colonic motility. There was no correlation between colinic motility and gastric emptying of a liquid meal (r = 0.23) (P > 0.05) or peripheral nerve conduction (r = 0.36) (P > 0.05). Neostigmine (0.5 mg, intramuscularly) or metoclopramide (20 mg, intravenously) increased colonic spike (P < 0.005) and motor (P < 0.005) activity in all diabetic subjects regardless of their symptoms. These studies suggest that patients with diabetes mellitus and severe constipation may have an autonomic neuropathy which leads to an absent postprandial gastrocolonic response.