Reduced monoamine oxidase activity in blood platelets from insulin-dependent diabetic subjects.

Insulin-dependent diabetics show a significant reduction in blood platelets' monoamine oxidase (MAO) activity when compared with age-matched and sex-matched controls. This does not appear to be the case for diabetics either on diet control or receiving oral hypoglycemic drugs. The important role of this enzyme in the regulation of the circulating levels of a number of monoamines known to have an inhibitory effect on insulin secretion may indicate the possible inclusion of the MAO/monoamine system in the pathophysiology of diabetes. The possibility of using platelets' MAO activity as a biologic marker for a subgroup of insulin-dependent diabetics is also discussed.