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

Abstract

This study was designed to compare the effects of two low-dose triphasic oral contraceptives (OCs) on glucose tolerance and insulin secretion. Fifty-seven women were randomized to receive OCs containing ethinyl estradiol and either levonorgestrel or norethindrone. Ten 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 months compared with baseline, but within the norms for glucose tolerance. The insulin response, measured in 48 treated and eight 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.