Table 2.
Multivariable-adjusted HRs (95% CIs) of incident diabetes by quintiles of B vitamin intake levels: the CARDIA study, 1985–2015*†‡§
| Quintiles of nutrient intake | Ptrend | |||||
|---|---|---|---|---|---|---|
| Q1 | Q2 | Q3 | Q4 | Q5 | ||
| Folate (n = 4,703) | ||||||
| Range (µg/day) | <281.6 | 281.6–393.4 | 393.4–508.4 | 508.4–693.5 | ≥693.5 | NA |
| Median (µg/day) | 216.4 | 338.9 | 450.0 | 591.2 | 885.7 | NA |
| No. of cases/participants | 147/940 | 150/941 | 125/941 | 132/941 | 101/940 | NA |
| Model 1 | 1 | 0.80 | 0.66 | 0.66 | 0.48 | <0.01 |
| [Ref.] | (0.63, 1.01) | (0.52, 0.86) | (0.51, 0.86) | (0.36, 0.64) | ||
| Model 2 | 1 | 0.93 | 0.81 | 0.84 | 0.68 | <0.01 |
| [Ref.] | (0.74, 1.18) | (0.63, 1.05) | (0.64, 1.09) | (0.50, 0.92) | ||
| Model 3 (final model) | 1 | 0.85 | 0.78 | 0.82 | 0.70 | 0.02 |
| [Ref.] | (0.67, 1.08) | (0.60, 1.02) | (0.62, 1.09) | (0.51, 0.97) | ||
| B6 (n = 3,894) | ||||||
| Range (mg/day) | <1.7 | 1.7–2.4 | 2.4–3.2 | 3.2–4.6 | ≥4.6 | NA |
| Median (mg/day) | 1.4 | 2.0 | 2.7 | 3.8 | 6.8 | NA |
| No. of cases/participants | 143/779 | 112/777 | 123/779 | 111/779 | 98/780 | NA |
| Model 1 | 1 | 0.74 | 0.84 | 0.75 | 0.64 | 0.06 |
| [Ref.] | (0.58, 0.96) | (0.65, 1.09) | (0.57, 0.99) | (0.48, 0.85) | ||
| Model 2 | 1 | 0.86 | 0.96 | 0.94 | 0.82 | 0.69 |
| [Ref.] | (0.66, 1.10) | (0.74, 1.25) | (0.71, 1.24) | (0.61, 1.11) | ||
| Model 3 (final model) | 1 | 0.89 | 1.07 | 1.06 | 1.04 | 0.40 |
| [Ref.] | (0.68, 1.15) | (0.80, 1.42) | (0.76, 1.47) | (0.71, 1.51) | ||
| B12 (n = 3,894) | ||||||
| Range (µg/day) | <4.1 | 4.1–6.1 | 6.1–8.7 | 8.7–13.8 | ≥13.8 | NA |
| Median (µg/day) | 3.0 | 5.1 | 7.3 | 10.6 | 21.0 | NA |
| No. of cases/participants | 120/778 | 131/779 | 121/780 | 104/778 | 111/779 | NA |
| Model 1 | 1 | 1.05 | 0.96 | 0.86 | 0.88 | 0.49 |
| [Ref.] | (0.82, 1.35) | (0.74, 1.25) | (0.65, 1.14) | (0.66, 1.16) | ||
| Model 2 | 1 | 1.08 | 1.02 | 0.99 | 1.08 | 0.46 |
| [Ref.] | (0.84, 1.39) | (0.79, 1.34) | (0.75, 1.31) | (0.81, 1.44) | ||
| Model 3 (final model) | 1 | 1.04 | 1.08 | 1.14 | 1.29 | 0.053 |
| [Ref.] | (0.80, 1.35) | (0.81, 1.44) | (0.83, 1.56) | (0.91, 1.84) | ||
NA, not applicable; Q, quintile; Ref., reference.
Cox proportional hazards regression models were used. Linear trend was examined by using the continuous variables that excluded the values above the 99th percentile. †Model 1 was adjusted for age, sex (female or male), race (White or Black), study center, and total energy intake (continuous). ‡Model 2 was additionally adjusted for education levels (<12, 12–15.9, ≥16 years), smoking status (never, former, or current smoker), alcohol consumption (0, 0.1–11.9, 12–23.9, ≥24 mL/day), physical activity levels (quintiles), and BMI (continuous). §Model 3 was additionally adjusted for glucose levels at baseline (continuous), HDL-c–to–LDL-c ratio (quintiles), TG (quintiles), family history of diabetes (parental, yes or no), and supplement use of B vitamin of interest (yes or no).