Oestradiol levels may differ between premenopausal women, ages 18-50, with type 1 diabetes and matched controls

This study aimed to investigate whether oestradiol differs between premenopausal women with and without type 1 diabetes and whether levels are associated with such factors as age, reproductive history or diabetes management.

Oestradiol in premenopausal women with type 1 diabetes (n = 89; age = 18-50 years; duration = 13-18 years) and age-matched/race-matched controls without diabetes (n = 76) was collected during a cross-sectional ancillary study of the Wisconsin Diabetes Registry Study, a population-based incident cohort. Total and bioavailable oestradiol and sex hormone-binding globulin were compared using multivariable regression (e.g. adjusting for reproductive history).

Adjusted mean total and bioavailable oestradiol did not differ overall by diabetes status (p ≥ 0.74), while adjusted mean sex hormone-binding globulin was higher in type 1 diabetes women (p = 0.02). However, only in women with type 1 diabetes and not controls (interaction p = 0.0005) was total oestradiol positively associated with the duration of reproductive years with unsuppressed ovarian function (UnsuppOvFx = years since menarche minus years on hormonal contraceptives/pregnant/breastfeeding). When stratified into less than/equal to or greater than the median 9 years' duration of UnsuppOvFx, compared with controls, women with type 1 diabetes had significantly lower total oestradiol in the ≤9 years group [β = -43.2 pg mL^-1 (-158.6 pmol L^-1 ), p = 0.04] and significantly higher total oestradiol in the >9 years group [β = 53.9 pg mL^-1 (197.9 pmol L^-1 ), p = 0.04]. Results remained consistent during additional statistical adjustments and sensitivity analyses.

Compared with controls, women with type 1 diabetes may have lower oestradiol when they have a shorter duration of UnsuppOvFx and higher oestradiol when they have a longer duration of UnsuppOvFx. Given the potential effects of insulin on ovarian function, oestradiol production may vary across the lifespan for women with type 1 diabetes. Copyright © 2016 John Wiley & Sons, Ltd.