Table 1.
Characteristics of study participants according to 25(OH)D quintiles
| Quintiles of 25(OH)D |
|||||
|---|---|---|---|---|---|
| Q1: ≤28.7nmol/l | Q2: 28.8–36.8 nmol/l | Q3: 36.9–45.5 nmol/l | Q4: 45.6–57.6 nmol/l | Q5: ≥57.7 nmol/l | |
| n | 652 | 653 | 652 | 653 | 652 |
| Age (years) | 58.8 ± 6.3 | 58.1 ± 6.0 | 58.8 ± 5.9 | 58.2 ± 5.9 | 59.1 ± 5.9 |
| Male sex | 233 (35.7) | 252 (38.6) | 279 (42.8) | 311 (47.6) | 368 (56.4) |
| Urban residents | 423 (64.9) | 384 (58.8) | 367 (56.3) | 260 (39.8) | 189 (29.0) |
| Residents of Beijing | 466 (71.5) | 419 (64.2) | 331 (50.8) | 238 (36.5) | 168 (25.8) |
| Visit date (April) | 433 (66.4) | 389 (59.6) | 334 (51.2) | 245 (37.5) | 183 (28.1) |
| Smoking | |||||
| Never | 395 (60.6) | 422 (64.6) | 423 (64.9) | 409 (62.6) | 376 (57.7) |
| Former | 67 (10.3) | 51 (7.8) | 63 (9.7) | 59 (9.0) | 87 (13.3) |
| Current | 190 (29.1) | 180 (27.6) | 166 (25.5) | 185 (28.3) | 189 (29.0) |
| Alcohol drinking, yes | 167 (25.6) | 183 (28.0) | 189 (29.0) | 193 (29.6) | 196 (30.1) |
| Physical activity | |||||
| Low | 63 (9.7) | 40 (6.1) | 47 (7.2) | 50 (7.7) | 43 (6.6) |
| Moderate | 310 (47.6) | 307 (47.0) | 294 (45.1) | 228 (34.9) | 230 (35.3) |
| High | 279 (42.8) | 306 (46.9) | 311 (47.7) | 375 (57.4) | 379 (58.1) |
| Education | |||||
| 0–6 years | 201 (30.8) | 223 (34.2) | 240 (36.8) | 317 (48.6) | 371 (56.9) |
| 7–9 years | 278 (42.6) | 254 (38.9) | 249 (38.2) | 201 (30.8) | 177 (27.2) |
| ≥10 years | 173 (26.5) | 176 (27.0) | 163 (25.0) | 135 (20.7) | 104 (16.0) |
| Hypertension* | 373 (57.2) | 372 (57.0) | 367 (56.3) | 329 (50.4) | 344 (52.8) |
| Self-reported CHD† | 67 (10.6) | 54 (8.4) | 48 (7.6) | 29 (4.6) | 28 (4.4) |
| Self-reported stroke‡ | 33 (5.1) | 32 (4.9) | 23 (3.5) | 24 (3.7) | 19 (2.9) |
| Family history of diabetes | 105 (16.1) | 89 (13.6) | 86 (13.2) | 93 (14.2) | 74 (11.4) |
| Family history of CVD | 179 (27.5) | 154 (23.6) | 152 (23.3) | 149 (22.8) | 97 (14.9) |
| BMI (kg/m2) | 24.9 ± 3.8 | 24.9 ± 3.8 | 24.6 ± 3.6 | 24.3 ± 3.2 | 23.5 ± 3.3 |
| Waist circumference (cm) | 85.2 ± 10.5 | 84.7 ± 10.7 | 84.2 ± 10.8 | 83.2 ± 10.1 | 81.3 ± 10.2 |
| Fasting glucose (mmol/l) | 5.52 (5.08–6.09) | 5.46 (5.09–6.00) | 5.46 (5.09–5.98) | 5.42 (4.99–5.88) | 5.28 (4.96–5.72) |
| A1C (%) | 5.76 (5.46–6.22) | 5.75 (5.48–6.14) | 5.73 (5.46–6.10) | 5.78 (5.47–6.11) | 5.68 (5.39–6.02) |
| Insulin (pmol/l)§ | 87.0 (61.2–123.0) | 87.0 (60.0–120.6) | 82.2 (61.2–113.4) | 80.7 (59.4–106.8) | 73.8 (55.2–99.3) |
| HOMA-IR‖ | 1.67 (1.18–2.30) | 1.66 (1.17–2.26) | 1.59 (1.18–2.12) | 1.52 (1.14–2.02) | 1.40 (1.07–1.88) |
| Triglycerides (mmol/l) | 1.15 (0.83–1.82) | 1.17 (0.82–1.80) | 1.15 (0.80–1.71) | 1.06 (0.73–1.61) | 0.92 (0.65–1.38) |
| HDL cholesterol (mmol/l) | 1.25 ± 0.34 | 1.27 ± 0.33 | 1.27 ± 0.33 | 1.27 ± 0.33 | 1.32 ± 0.33 |
| CRP (mg/l) | 0.79 (0.36–1.92) | 0.74 (0.35–1.68) | 0.67 (0.33–1.49) | 0.60 (0.32–1.37) | 0.59 (0.29–1.25) |
| IL-6 (pg/ml)¶ | 1.13 (0.73–1.86) | 1.07 (0.73–1.65) | 1.00 (0.62–1.49) | 1.06 (0.69–1.57) | 0.94 (0.61–1.49) |
Data are means ± SD, n (%), or median (interquartile range).
*Blood pressure ≥140/90 mmHg, or current use of anti-hypertensive medications.
†77 participants were excluded with a missing value for self-reported CHD.
‡10 participants were excluded with a missing value for self-reported stroke.
§4 participants were excluded with a missing value of fasting insulin.
‖23 participants were excluded with a missing value for HOMA-IR.
¶89 participants were excluded with a missing value for IL-6.