Effect of Diphenylhydantoin on Insulin Secretion in Man

Abstract

Blood glucose and serum insulin levels were measured in six normal subjects receiving an intravenous glucose priming load followed by a 2 1/2-hour constant glucose infusion. The test procedure was repeated in these subjects after three days of oral diphenylhydantoin (DPH) therapy (200 mg, three times daily). During both series of tests, high blood glucose levels were achieved throughout the infusion, and diphasic insulin responses were observed, characterized by an early peak and a late rise. DPH administration resulted in a significantly higher mean blood glucose response (+ 19 per cent, p less than 0.01) and significant diminution of early and late insulin responses (respectively, -60 per cent, p less than 0.01, and -39 per cent, p less than 0.05).