Cross-sectional association of coffee and caffeine consumption with sex hormone-binding globulin in healthy nondiabetic women

Objective: Low sex hormone-binding globulin (SHBG) is a consistent risk factor for type 2 diabetes, particularly in women. Coffee consumption has been associated with a lower risk of type 2 diabetes, but its effects on SHBG are less known. Design and methods: This was a cross-sectional study of 2377 nondiabetic pre- and postmenopausal women from the E3N cohort study whose baseline SHBG was measured. Information on diet (including coffee and caffeine consumption), lifestyle and medical conditions was collected through questionnaires. The relationship between coffee and caffeine consumption and SHBG was modelled, with adjustment for covariates and stratification by body mass index (BMI) categories (< or 25kg/m(2)) and menopausal status. Results: The mean age was 57.26.4years and 61% of the 2377 women were postmenopausal. High coffee (3cups/day) and caffeine (265mg/day) intakes were associated with a reduced risk of being in the 1st quartile of the SHBG level distribution (<46.3nmol/L) in a multivariate adjusted model (OR: 0.72 [95% CI: 0.52-1.01] and OR: 0.71 [95% CI: 0.53-0.95], respectively). No association was found between tea consumption and SHBG levels. In multivariate models stratified on BMI categories and menopausal status, associations were restricted to women with a BMI 25kg/m(2) or being postmenopausal. The association with SHBG was consistently noted with consumption of both caffeinated coffee and caffeine, but not decaffeinated coffee. Conclusions: Consumption of high coffee and caffeine is associated with a reduced risk of low SHBG, an established risk marker for T2DM, which might contribute to the protective effects of coffee for type 2 diabetes.