Mechanism of Action of Phenethylbiguanide in Normal Subjects

Administration of phenethylbiguanide (DBI) to fifteen normal adult controls in a single dose of 200 mg. had no effect on fasting blood sugar. DBI increased the tolerance to glucose and insulin responsivity, provided that glucose was given simultaneously in the latter test. It is suggested that the hypoglycemic action of DBI in healthy peopleis only evident when adequate substrate (glucose) is available in the presence of insulin to “push” glucose entry into the cell. That it is not simple potentiation ofinsulin action is suggested by a smaller decline in free fatty acids (FFA) during intravenous glucose infusion despite a greater increase in glucose.