[Diurnal variation in glucose tolerance in rats after experimental changes in glucocorticoid rhythm]

Control rats manifested an unmarked circadian rhythm in blood sugar during evening hours. The morning-evening difference in blood sugar increased after adrenalectomy, disappeared after weekly substitution therapy with cortisol and was inverted after evening injections of cortisol to rats with intact adrenals. Evening injections of the hormone were also more efficacious from the standpoint of glucose tolerance modulation.