Glucose and insulin levels after six months of treatment with a triphasic oral contraceptive containing ethinyl estradiol and norethindrone.

To evaluate the effects of a triphasic oral contraceptive (OC) containing ethinyl estradiol and norethindrone on carbohydrate metabolism both blood glucose and insulin levels were measured over the 6-month study period in 33 new acceptors. An identical oral glucose tolerance test was administered to each study subject immediately before commencing OC use and again during the 6th cycle of treatment; thus each subject served as her own control. All glucose tolerance test results were normal and all fasting values were under 100 mg%. The only change accompanying triphasic OC use was a significant decrease in fasting glucose values. Mean control levels of plasma glucose (mg%) were 74.1 after a 10-hour fast and 113.4 94.9 89.7 and 86.2 0.5 1 2 and 3 hours respectively after consumption of 100 grams of glucose. 6-month levels averaged 70.2 at fasting 115.3 at 0.5 hours 102.3 at 1 hour 92.8 at 2 hours and 87.5 at 3 hours. The mean total insulin value was 213.7 + or - 27.4 mcgU pretreatment and 218.5 + or - 17.3 after 6 months of OC use--a nonsignificant difference. Earlier studies have demonstrated alterations in carbohydrate metabolism in users of high-dose OCs presumably attributable to the progestogen component. Triphasic formulations achieve maximum reduction of the progestogen content of OCs by using 3 different doses throughout the month. Future longterm studies of users of low-dose and triphasic OCs are expected to show minimal clinical sequelae in the vascular systems of users.