TABLE 4.
ORs for type 2 diabetes according to caffeinated coffee, decaffeinated coffee, tea, and caffeine consumption
| 0 cups/day | ≤1 cups/day | 2–3 cups/day | ≥4 cups/day | P for trend* | |
|---|---|---|---|---|---|
| Caffeinated coffee (case subjects/control subjects) | 99/86 | 103/84 | 105/107 | 49/73 | |
| Median (cups/day) | 0 | 1.0 | 2.5 | 4.5 | |
| Match-adjusted model† | 1.00 | 1.04 (0.68–1.60) | 0.82 (0.55–1.23) | 0.55 (0.34–0.90) | 0.008 |
| Categorical model‡ | 1.00 | 0.95 (0.52–1.74) | 0.94 (0.53–1.67) | 0.47 (0.23–0.94) | 0.047 |
| Categorical model + SHBG§ | 1.00 | 0.92 (0.46–1.84) | 0.96 (0.48–1.94) | 0.71 (0.31–1.61) | 0.47 |
| Spline model‖ | 1.00 | 1.11 (0.63–1.97) | 0.92 (0.55–1.54) | 0.61 (0.34–1.11) | |
| Spline model + SHBG¶ | 1.00 | 0.87 (0.45–1.68) | 0.86 (0.47–1.58) | 0.80 (0.39–1.65) | |
| Decaffeinated coffee (case subjects/control subjects) | 211/190 | 94/94 | 37/47 | 8/15 | |
| Median (cups/day) | 0 | 0.4 | 2.5 | 4.5 | |
| Match-adjusted model† | 1.00 | 0.87 (0.60–1.26) | 0.63 (0.38–1.03) | 0.49 (0.20–1.20) | 0.03 |
| Categorical model‡ | 1.00 | 1.16 (0.70–1.95) | 0.77 (0.38–1.55) | 0.72 (0.19–2.69) | 0.39 |
| Categorical model + SHBG§ | 1.00 | 1.03 (0.56–1.90) | 1.11 (0.46–2.71) | 1.33 (0.27–6.49) | 0.71 |
| Spline model‖ | 1.00 | 1.30 (0.90–1.88) | 0.61 (0.33–1.14) | 0.47 (0.17–1.29) | |
| Spline model + SHBG¶ | 1.00 | 1.31 (0.84–2.03) | 0.91 (0.42–2.00) | 0.92 (0.26–3.27) | |
| Tea (case subjects/control subjects) | 114/128 | 180/171 | 37/39 | 18/10 | |
| Median (cups/day) | 0 | 0.4 | 2.5 | 4.5 | |
| Match-adjusted model† | 1.00 | 1.21 (0.87–1.69) | 1.06 (0.64–1.74) | 2.03 (0.91–4.54) | 0.23 |
| Categorical model‡ | 1.00 | 1.12 (0.70–1.77) | 1.22 (0.59–2.50) | 1.53 (0.43–5.47) | 0.46 |
| Categorical model + SHBG§ | 1.00 | 0.97 (0.55–1.72) | 1.14 (0.48–2.72) | 1.74 (0.44–6.93) | 0.42 |
| Spline model‖ | 1.00 | 1.39 (0.99–1.93) | 1.52 (0.83–2.77) | 1.32 (0.51–3.38) | |
| Spline model + SHBG¶ | 1.00 | 1.37 (0.93–2.03) | 1.37 (0.67–2.78) | 1.57 (0.54–4.58) | |
| Caffeine category (mg/day) | ≤50 | 51–250 | 251–500 | >500 | |
| Caffeine intake (mg/day), median | 13 | 140 | 366 | 656 | |
| (case subjects/control subjects) | 67/64 | 109/100 | 118/112 | 49/74 | |
| Match-adjusted model† | 1.00 | 1.01 (0.65–1.56) | 0.99 (0.63–1.54) | 0.62 (0.37–1.04) | 0.06 |
| Categorical model‡ | 1.00 | 1.00 (0.56–1.82) | 1.26 (0.68–2.32) | 0.56 (0.27–1.15) | 0.18 |
| Categorical model + SHBG§ | 1.00 | 0.94 (0.47–1.88) | 1.44 (0.68–3.04) | 0.89 (0.38–2.10) | 0.91 |
| Spline model‖ | 1.00 | 1.56 (0.80–3.04) | 1.56 (0.81–3.01) | 0.92 (0.48–1.76) | |
| Spline model + SHBG¶ | 1.00 | 1.53 (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.