Effect of long-term triphasic oral contraceptive use on glucose tolerance and insulin secretion

This study was designed to compare the effects of 2 low-dose triphasic oral contraceptives (OCs) on glucose tolerance and insulin secretion. 57 women were randomized to receive OCs containing ethinyl estradiol and either levonorgestrel or norethindrone. 10 subjects using nonhormonal contraception served as controls. Glucose tolerance and insulin secretion were measured at baseline and at 6 and 12 months after an oral glucose stimulus. Both preparations produced a relative hyperglycemia at 6 and 12 month compared with baseline but within the norms for glucose tolerance. The insulin response measured in 48 treated and 8 control subjects also increased over 12 months in both treated groups but the total insulin area was within the range of the reference laboratory. Such minor changes have not been associated with cardiovascular diseases and support the safety of low-dose triphasic preparations. (authors)