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October 8, 1973

Diphenylhydantoin and Early Diabetes

JAMA. 1973;226(2):191. doi:10.1001/jama.1973.03230020041014

In addition to its anticonvulsant and antiarrhythmic actions, diphenylhydantoin is known to produce a hyperglycemic effect. So potent is the latter that it may conceal the presence of an insulin-secreting tumor in a patient receiving the drug for epilepsy, as reported by Knopp et al.1 Whether this hyperglycemic agent, which can mask insulinoma, could through the same mechanism unmask defects of insulin secretion early in diabetes is the subject of a recent study by Levin and associates.2 Insulin responses to two secretory stimuli—glucose and postglucose arginine—before and after a course of diphenylhydantoin, in seven nonobese subjects manifesting mild oral glucose intolerance, were compared with responses in eight matched nonobese glucose-tolerant subjects. No important difference in insulin release was observed between the two groups before they received diphenylhydantoin. Nor was there a difference after the drug had been taken for several days in the glucose-provoked insulin release. But there