[Phenytoin treatment of motor diarrhea in diabetic patients]

Phenytoin (diphenylhydantoin) was used in doses of 300 mg/24 hours to treat severe motor diarrhoea in 5 diabetic patients. The patients had been insulin-dependent for 2 to 17 years and had advanced neuropathy. In each case, malabsorption, lesions of the colon or small bowel, endocrine tumour or parasitic, infectious and inflammatory causes could be excluded. Under phenytoin the diarrhoea ceased in all 5 patients within 24 to 48 hours. It recurred in 4 of them within 48 hours when treatment was withdrawn to disappear within the same length of time when it was reintroduced. No relapse was observed for periods of 3 months to 5 years under phenytoin maintenance treatment. The mechanism of action of phenytoin may suggest that diabetic diarrhoea is hormone-mediated or caused by an effect on the autonomous nervous system or on the peptidergic system, but no definite conclusion can be reached in the present state of our knowledge.