EFFECTS OF ORAL CONTRACEPTIVES AND THEIR COMPONENTS ON GLUCOSE TOLERANCE IN RATS

ABSTRACT Treatment of adult female spayed rats with norgestrel, ethynyl oestradiol and their combination (Ovral®) at doses approximating 1 and 25 fold multiples of the human dose protected them against the combined diabetogenic influence of a glucose load and the hyperglycaemic effect of reduced insulin B-chain. Norgestrel and Ovral® appeared to be antidiabetogenic since they reversed the B-chain-induced hyperglycaemia. Various steroidal contraceptives and certain of their components failed to modify B-chain-induced hyperglycaemia in spayed rats sensitized with a high fat, high protein diet. Normal intact female rats treated with norgestrel, ethynyl oestradiol and their combinations and given glucose tolerance tests produced glucose responses higher than those of controls, but since these groups showed recovery to or toward control blood glucose levels, insulin mobilization was apparently normal. In a second experiment, Ovral® and various contraceptive formulations failed to produce significant alterations in glucose tolerance. None of these studies suggested a diabetogenic effect of the contraceptive steroids employed; in fact, the first study with reduced insulin B-chain suggested an anti-diabetogenic effect for Ovral®.