Stimulation of alpha₂-adrenergic receptors on enterocytes promotes fluid and electrolyte absorption and inhibits anion secretion. Loss of adrenergic innervation may play a role in impaired intestinal fluid and electrolyte absorption in diabetic patients with autonomic neuropathy. Clonidine, an alpha₂-adrenergic agonist, was used to treat three patients with "idiopathic" diabetic diarrhea after other treatments had failed: The volume of diarrhea declined significantly (p < 0. 01). Diarrhea recurred when the drug was withdrawn, but the patient's condition improved again when Clonidine treatment was reintroduced. Hypotension did not occur as a side effect presumably because of the autonomic neuropathy of these patients.