Table 1

Characteristics of study participants according to 25(OH)D quintiles

Quintiles of 25(OH)D
Q1: ≤28.7nmol/lQ2: 28.8–36.8 nmol/lQ3: 36.9–45.5 nmol/lQ4: 45.6–57.6 nmol/lQ5: ≥57.7 nmol/l
n652653652653652
Age (years)58.8 ± 6.358.1 ± 6.058.8 ± 5.958.2 ± 5.959.1 ± 5.9
Male sex233 (35.7)252 (38.6)279 (42.8)311 (47.6)368 (56.4)
Urban residents423 (64.9)384 (58.8)367 (56.3)260 (39.8)189 (29.0)
Residents of Beijing466 (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
    Never395 (60.6)422 (64.6)423 (64.9)409 (62.6)376 (57.7)
    Former67 (10.3)51 (7.8)63 (9.7)59 (9.0)87 (13.3)
    Current190 (29.1)180 (27.6)166 (25.5)185 (28.3)189 (29.0)
Alcohol drinking, yes167 (25.6)183 (28.0)189 (29.0)193 (29.6)196 (30.1)
Physical activity
    Low63 (9.7)40 (6.1)47 (7.2)50 (7.7)43 (6.6)
    Moderate310 (47.6)307 (47.0)294 (45.1)228 (34.9)230 (35.3)
    High279 (42.8)306 (46.9)311 (47.7)375 (57.4)379 (58.1)
Education
    0–6 years201 (30.8)223 (34.2)240 (36.8)317 (48.6)371 (56.9)
    7–9 years278 (42.6)254 (38.9)249 (38.2)201 (30.8)177 (27.2)
    ≥10 years173 (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 CHD67 (10.6)54 (8.4)48 (7.6)29 (4.6)28 (4.4)
Self-reported stroke33 (5.1)32 (4.9)23 (3.5)24 (3.7)19 (2.9)
Family history of diabetes105 (16.1)89 (13.6)86 (13.2)93 (14.2)74 (11.4)
Family history of CVD179 (27.5)154 (23.6)152 (23.3)149 (22.8)97 (14.9)
BMI (kg/m2)24.9 ± 3.824.9 ± 3.824.6 ± 3.624.3 ± 3.223.5 ± 3.3
Waist circumference (cm)85.2 ± 10.584.7 ± 10.784.2 ± 10.883.2 ± 10.181.3 ± 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-IR1.67 (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 ± 0.341.27 ± 0.331.27 ± 0.331.27 ± 0.331.32 ± 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.