Comparison of ethinylestradiol and mestranol in sequential-type oral contraceptives in their effects on blood glucose and serum insulin in oral glucose tolerance tests.

Forty 3-hour oral glucose tolerance tests (OGTTs) were performed in 10 assumedly healthy female volunteers 19 to 30 years old, each serving four times as her own control. Each subject was taking a sequential type oral contraceptive containing either 50 microgram of ethinylestradiol or 80 microgram of mestranol alternatingly in four consecutive treatment cycles. The OGTTs were performed on the 6th day of each cycle, during pure estrogen medication. Blood glucose and serum insulin values did not differ significantly under either estrogen as tested by the t-test for paired observations. Our results do not support the findings of others that mestranol has a more pronounced or even exclusively adverse effect on glucose tolerance as compared with ethinylestradiol.