Table 1. General characteristics of Korean prediabetic adults by serum 25(OH)D level.
| Serum 25(OH)D groups by IOM criteria a | |||||
|---|---|---|---|---|---|
| Total | < 12 ng/ml | 12 to < 20 ng/ml | ≥ 20 ng/ml | P value | |
| (n = 60) | (n = 14) | (n = 31) | (n = 15) | ||
| Sex (%) | |||||
| Male | 31 (51.7) b | 5 (35.7) | 18 (58.1) | 8 (53.3) | 0.387 |
| Age (y) | 45.1 ± 1.4 c | 43.5 ± 3.2 | 43.7 ± 1.8 | 49.4 ± 3.1 | |
| Smoking (%) | |||||
| Never | 40 (66.7) | 12 (85.7) | 17 (54.8) | 17 (73.3) | 0.090 |
| Former | 2 (3.3) | 1 (7.1) | 1 (3.2) | 0 (0.0) | |
| Current | 18 (30.0) | 1 (7.2) | 13 (42.0) | 4 (26.7) | |
| Drinking alcohol (%) | |||||
| Never | 16 (26.7) | 5 (35.7) | 6 (19.4) | 5 (33.3) | 0.693 |
| Former | 1 (1.7) | 0 (0.0) | 1 (3.2) | 0 (0.0) | |
| Current | 43 (71.7) | 9 (64.3) | 24 (77.4) | 10 (66.7) | |
| Season of blood draw (%) | |||||
| Late spring and summer | 24 (40.0) | 8 (57.1) | 13 (41.9) | 3 (20.0) | 0.042 |
| Fall | 36 (60.0) | 6 (42.9) | 18 (58.1) | 12 (80.0) | |
| Daytime outdoor activity (%) | |||||
| 6~7/week | 12 (20.0) | 1 (7.1) | 4 (12.9) | 7 (46.7) | 0.019 |
| 3~5/week | 7 (11.7) | 3 (21.4) | 1 (3.2) | 3 (20.0) | |
| 1~2/week | 19 (31.7) | 5 (35.7) | 12 (38.7) | 2 (13.3) | |
| Never | 22 (36.7) | 5 (35.7) | 14 (45.2) | 3 (20.0) | |
| Skin color (%) | |||||
| Light | 9 (15.0) | 4 (28.6) | 5 (16.1) | 0 (0.0) | 0.081 |
| Medium | 39 (65.0) | 9 (64.3) | 17 (54.8) | 13 (86.7) | |
| Dark | 12 (20.0) | 1 (7.1) | 9 (29.0) | 2 (13.3) | |
| Sunblock (%) | |||||
| User | 24 (40.0) | 5 (35.7) | 13 (41.9) | 6 (40.0) | 0.941 |
| Energy intake (kcal/day) | 1565.0 ± 63.8 | 1514.4 ± 76.5 | 1551.9 ± 108.8 | 1639.2 ± 103.0 | 0.363 |
| Total fat intake (g/day) | 41.8 ± 2.1 | 39.3 ± 3.4 | 40.4 ± 3.2 | 47.1 ± 3.8 | 0.196 |
| Vitamin D intake (μg/day) | 3.1 ± 0.4 | 2.9 ± 0.5 | 2.6 ± 0.3 | 3.9 ± 1.2 | 0.741 |
| Vitamin D intake (%, KDRIs) d | 30.0 ± 3.7 | 29.3 ± 4.7 | 25.8 ± 3.5 | 39.4 ± 12.3 | 0.689 |
25(OH)D, 25-hydroxyvitamin D; IOM, Institute of Medicine
a 25(OH)D levels were classified according to diagnostic criteria defined by IOM in 2011.
b Values are n (%); difference among serum 25(OH)D group was assessed by the Fisher’s exact test.
c Values are mean ± SE; difference among serum 25(OH)D group was assessed by the Kruskal-Wallis test.
d Percentage of daily intake of vitamin D compared with the quantity suggested by dietary reference intakes for Koreans (KDRIs).