TABLE 4

ORs for type 2 diabetes according to caffeinated coffee, decaffeinated coffee, tea, and caffeine consumption

0 cups/day≤1 cups/day2–3 cups/day≥4 cups/dayP for trend*
Caffeinated coffee (case subjects/control subjects)99/86103/84105/10749/73
    Median (cups/day)01.02.54.5
    Match-adjusted model1.001.04 (0.68–1.60)0.82 (0.55–1.23)0.55 (0.34–0.90)0.008
    Categorical model1.000.95 (0.52–1.74)0.94 (0.53–1.67)0.47 (0.23–0.94)0.047
    Categorical model + SHBG§1.000.92 (0.46–1.84)0.96 (0.48–1.94)0.71 (0.31–1.61)0.47
    Spline model1.001.11 (0.63–1.97)0.92 (0.55–1.54)0.61 (0.34–1.11)
    Spline model + SHBG1.000.87 (0.45–1.68)0.86 (0.47–1.58)0.80 (0.39–1.65)
Decaffeinated coffee (case subjects/control subjects)211/19094/9437/478/15
    Median (cups/day)00.42.54.5
    Match-adjusted model1.000.87 (0.60–1.26)0.63 (0.38–1.03)0.49 (0.20–1.20)0.03
    Categorical model1.001.16 (0.70–1.95)0.77 (0.38–1.55)0.72 (0.19–2.69)0.39
    Categorical model + SHBG§1.001.03 (0.56–1.90)1.11 (0.46–2.71)1.33 (0.27–6.49)0.71
    Spline model1.001.30 (0.90–1.88)0.61 (0.33–1.14)0.47 (0.17–1.29)
    Spline model + SHBG1.001.31 (0.84–2.03)0.91 (0.42–2.00)0.92 (0.26–3.27)
Tea (case subjects/control subjects)114/128180/17137/3918/10
    Median (cups/day)00.42.54.5
    Match-adjusted model1.001.21 (0.87–1.69)1.06 (0.64–1.74)2.03 (0.91–4.54)0.23
    Categorical model1.001.12 (0.70–1.77)1.22 (0.59–2.50)1.53 (0.43–5.47)0.46
    Categorical model + SHBG§1.000.97 (0.55–1.72)1.14 (0.48–2.72)1.74 (0.44–6.93)0.42
    Spline model1.001.39 (0.99–1.93)1.52 (0.83–2.77)1.32 (0.51–3.38)
    Spline model + SHBG1.001.37 (0.93–2.03)1.37 (0.67–2.78)1.57 (0.54–4.58)
Caffeine category (mg/day)≤5051–250251–500>500
Caffeine intake (mg/day), median13140366656
    (case subjects/control subjects)67/64109/100118/11249/74
    Match-adjusted model1.001.01 (0.65–1.56)0.99 (0.63–1.54)0.62 (0.37–1.04)0.06
    Categorical model1.001.00 (0.56–1.82)1.26 (0.68–2.32)0.56 (0.27–1.15)0.18
    Categorical model + SHBG§1.000.94 (0.47–1.88)1.44 (0.68–3.04)0.89 (0.38–2.10)0.91
    Spline model1.001.56 (0.80–3.04)1.56 (0.81–3.01)0.92 (0.48–1.76)
    Spline model + SHBG1.001.53 (0.71–3.30)1.70 (0.79–3.62)1.32 (0.61–2.82)
  • Data are OR (95% CI) unless otherwise indicated.

  • *P for trend values are based on median levels in categories.

  • †Match-adjusted model: stratified on matched pairs using conditional logistic regression models.

  • ‡Categorical model: further adjusted for smoking status, physical activity, family history of diabetes, alcohol use, total calories, and BMI.

  • §Categorical model + SHBG: further adjusted for plasma SHBG.

  • ‖Spline model: ORs comparing odds at category medians from quadratic logistic spline models with one knot at the middle category boundaries adjusted for covariates used in categorical model.

  • ¶Spline model + plasma SHBG: further adjusted for plasma SHBG.