Long-term effects of oral contraceptives on the prevalence of diabetes in post-menopausal women: 2007-2012 KNHANES.

There is little information on whether past use of oral contraceptives (OCs) at child-bearing age influences the incidences of diabetes and insulin resistance (IR) after menopause. This study aimed to evaluate the association of past use of OCs with the development of diabetes and IR in post-menopausal women. This cross-sectional study was based on data from the Korea National Health and Nutrition Examination Survey carried out from 2007 to 2012. Of the 50405 participants, 6554 post-menopausal women were included in the analysis. The associations of OC use with the prevalence of diabetes in post-menopausal women were examined using multivariate logistic analysis. In addition, fasting glucose and insulin levels were measured in 3338 nondiabetic post-menopausal women, and the association between IR and OCs was examined by the analysis of covariance. The prevalence of diabetes was significantly higher in post-menopausal participants who had taken OCs for more than 6 months than in those who had never taken OCs. The association remained significant after adjusting for multiple confounding factors (odd ratio 1.379; 95 % CI 1.115-1.707; P = 0.003). The duration of OC use was also positively associated with the prevalence of diabetes. Furthermore, taking OCs for more than 6 months led to a significant increase in fasting insulin levels and HOMA-IR in nondiabetic participants. Past use of OCs for more than 6 months led to a significant increase in the prevalence of diabetes in post-menopausal women, and increased IR in nondiabetic participants. These results suggested that the prolonged use of OCs at reproductive age may be an important risk factor for developing diabetes in post-menopausal women.