Coffee and Caffeine Consumption in Relation to Sex Hormone–Binding Globulin and Risk of Type 2 Diabetes in Postmenopausal Women

TABLE 2

Geometric mean levels of plasma SHBG (nmol/l) according to caffeinated coffee, decaffeinated coffee, tea, and caffeine consumption

Categories of intake *P for trend
0 cups/day ≤1 cups/day 2–3 cups/day ≥4 cups/day
Caffeinated coffee, median (n) 0 (185) 1.0 (187) 2.5 (212) 4.5 (122)
    Match-adjusted model§ 23.1 (16.1–33.1) 22.7 (15.8–32.7) 24.7 (17.2–35.5) 27.6 (19.1–39.9) 0.002
    Categorical model 23.0 (16.5–32.0) 22.8 (16.3–31.8) 23.6 (16.9–33.0) 26.6 (18.9–37.4) 0.01
    Spline model 22.9 (16.5–31.9) 22.7 (16.2–31.8) 24.1 (17.2–33.6) 26.0 (18.5–36.5)
Decaffeinated coffee, median (n) 0 (401) 0.4 (188) 2.5 (84) 4.5 (23)
    Match-adjusted model§ 24.5 (17.1–35.2) 24.3 (16.8–35.4) 25.2 (17.1–37.3) 26.7 (17.4–40.9) 0.44
    Categorical model 23.7 (17.0–33.1) 22.3 (15.8–31.3) 23.2 (16.2–33.3) 22.9 (15.5–33.9) 0.75
    Spline model 23.6 (16.9–32.9) 23.5 (16.8–33.0) 23.6 (16.5–33.6) 23.5 (16.2–34.3)
Tea, median (n) 0 (242) 0.4 (351) 2.5 (76) 4.5 (28)
    Match-adjusted model§ 25.6 (17.9–36.7) 23.6 (16.4–33.8) 24.6 (16.9–35.8) 21.6 (14.3–32.5) 0.27
    Categorical model 24.5 (17.6–34.1) 23.3 (16.7–32.6) 23.3 (16.5–32.8) 21.4 (14.7–31.3) 0.24
    Spline model 24.4 (17.5–33.9) 23.7 (17.0–33.1) 22.5 (16.1–31.5) 22.7 (15.9–32.3)
Caffeine category (mg/day) ≤50 51–250 251–500 >500
Caffeine intake (mg/day), median (n) 13 (131) 140 (209) 366 (230) 656 (123)
    Match-adjusted model§ 22.9 (15.8–33.0) 22.5 (15.6–32.5) 23.6 (16.4–34.0) 26.9 (18.5–39.0) 0.008
    Categorical model 22.9 (16.5–32.0) 23.2 (16.7–32.3) 23.0 (16.5–32.1) 26.6 (19.0–37.4) 0.02
    Spline model 23.0 (16.5–32.1) 23.0 (16.6–32.0) 23.7 (17.0–33.0) 25.6 (18.3–35.8)
  • Data are geometric means (95% CI) unless otherwise indicated.

  • *P values for trend are based on median values in categories of the participants.

  • §Match-adjusted model: adjusted for age, race, duration of follow-up, and time of blood draw.

  • †Categorical model: adjusted for matching factors, smoking status, physical activity, alcohol use, total calories, and BMI.

  • ‡Spline model: estimates at category medians from quadratic spline regression models with one knot at the middle category boundaries, adjusted for covariates used in categorical model.

This Article

  1. Diabetes vol. 60 no. 1 269-275