Table 1 Characteristics by vitamin D status of Caucasian and African American ARIC study participants classified as having diabetes, with gradable eye photo at visit 3 (1993–95), and available serum 25(OH)D concentrations at visit 2 (1990–92) (N = 1339)
| Â | N | Vitamin D status defined by serum 25(OH)D concentrations (nmol/L) | p value | r (p value)a | |||
|---|---|---|---|---|---|---|---|
<30 deficient n = 96 (7 %) | 30 to <50 Inadequate n = 454 (34 %) | 50 to <75 Adequate n = 577 (43 %) | ≥75 adequate n = 212 (16 %) |  |  | ||
Season-adjusted serum 25(OH)D, mean (SD) | 1339 | 24.5 (4.9) | 41.7 (5.5) | 61.2 (6.9) | 88.6 (15.2) | <0.001 | NA |
Prevalence of retinopathy, n (% yes) | 1339 | 28 (29.2 %) | 111 (24.4 %) | 115 (19.9 %) | 26 (12.3 %) | <0.001 | § |
Severity of retinopathy, n (%) |  |  |  |  |  | 0.005 | § |
 None | 1059 | 68 (70.8 %) | 343 (75.6 %) | 462 (80.1 %) | 186(87.7 %) |  |  |
 Mild NPDR | 207 | 22 (22.9 %) | 82 (18.1 %) | 88 (15.3 %) | 15 (7.1 %) |  |  |
 Moderate/severe NPDR | 44 | 3 (3.1 %) | 21 (4.6 %) | 15 (2.6 %) | 5 (2.4 %) |  |  |
 Proliferative DR | 29 | 3 (3.1 %) | 8 (1.8 %) | 12 (2.1 %) | 6 (2.8 %) |  |  |
Demographics | |||||||
 Age (years), mean (SD) | 1339 | 56.4 (5.7) | 57.0 (5.6) | 57.7 (5.6) | 57.9 (5.5) | 0.046 | 0.08 (0.003) |
 Sex, n (% women) | 1339 | 78 (81.3 %) | 293 (64.5 %) | 254 (44.0 %) | 85 (40.1 %) | <0.001 | § |
 Race, n (% Caucasians) | 1339 | 38 (39.6 %) | 249 (54.8 %) | 428 (74.2 %) | 191 (90.1 %) | <0.001 | § |
 Field center, n (%) |  |  |  |  |  | <0.001 | § |
Forsyth County, NC | 308 | 20 (20.8Â %) | 92 (20.3Â %) | 136 (23.6Â %) | 60 (28.3Â %) | Â | Â |
 Jackson, MS | 374 | 50 (52.1 %) | 168 (37.0 %) | 137 (23.7 %) | 19 (9.0 %) |  |  |
 Minneapolis, MN | 286 | 14 (14.6 %) | 83 (18.3 %) | 136 (23.6 %) | 53 (25.0 %) |  |  |
 Washington County, MD | 371 | 12 (12.5 %) | 111 (24.4 %) | 168 (29.1 %) | 80 (37.7 %) |  |  |
Educationb, n (%)—visit 1 |  |  |  |  |  | 0.025 | § |
 Basic or 0 years | 370 | 25 (26.0 %) | 126 (27.9 %) | 154 (26.7 %) | 65 (30.7 %) |  |  |
 Intermediate | 559 | 34 (35.4 %) | 193 (42.8 %) | 230 (39.9 %) | 102 (48.1 %) |  |  |
 Advanced | 407 | 37 (38.5 %) | 132 (29.3 %) | 193 (33.4 %) | 45 (21.2 %) |  |  |
Health and lifestyle characteristics | |||||||
Duration of diabetes, n (%)—visit 3 |  |  |  |  |  | 0.572 | § |
 <3 years | 300 | 26 (27.1 %) | 89 (19.6 %) | 131 (22.7 %) | 54 (25.5 %) |  |  |
 3 to <6 years | 293 | 18 (18.8 %) | 106 (23.3 %) | 125 (21.7 %) | 44 (20.8 %) |  |  |
 ≥6 years | 746 | 52 (54.2 %) | 259 (57.0 %) | 321 (55.6 %) | 114 (53.8 %) |  |  |
Smoking status, n (%) |  |  |  |  |  | 0.034 | § |
 Current | 257 | 21 (21.9 %) | 97 (21.5 %) | 105 (18.2 %) | 34 (16.0 %) |  |  |
 Former | 535 | 30 (31.3 %) | 168 (37.2 %) | 232 (40.2 %) | 105 (49.5 %) |  |  |
 Never | 545 | 45 (46.9 %) | 187 (41.4 %) | 240 (41.6 %) | 73 (34.4 %) |  |  |
Vitamin D intake (IU/day), mean (SD)—visit 1 | 1305 | 164.2 (117.3) | 232.5 (154.4) | 239.7 (151.7) | 261.8 (147.4) | <0.001 | 0.16 (<0.001) |
Vitamin D supplement, n (% yes)—visit 3 | 1330 | 0 (0.0 %) | 8 (1.8 %) | 9 (1.6 %) | 6 (2.8 %) | 0.352 | § |
Fish oil supplement use, n (% yes)—visit 3 | 1330 | 0 (0.0 %) | 13 (2.9 %) | 12 (2.1 %) | 6 (2.8 %) | 0.362 | § |
Drinking status, n (%) |  |  |  |  |  | 0.056 | § |
 Current | 616 | 37 (38.5 %) | 191 (42.2 %) | 277 (48.0 %) | 111 (52.4 %) |  |  |
 Former | 364 | 24 (25.0 %) | 131 (28.9 %) | 155 (26.9 %) | 54 (25.5 %) |  |  |
 Never | 358 | 35 (36.5 %) | 131 (28.9 %) | 145 (25.1 %) | 47 (22.2 %) |  |  |
Waist circumference (cm), mean (SD) | 1337 | 112.2 (15.5) | 109.2 (15.8) | 106.9 (13.2) | 102.9 (12.5) | <0.001 | −0.16 (<0.001) |
BMI category (kg/m2), n (%) |  |  |  |  |  | <0.001 | −0.19 (<0.001) |
 Under/normal weight (<25 kg/m2) | 164 | 6 (6.3 %) | 45 (10.0 %) | 70 (12.2 %) | 43 (20.4 %) |  |  |
 Overweight (25–30 kg/m2) | 427 | 24 (25.0 %) | 135 (29.9 %) | 182 (31.6 %) | 86 (40.8 %) |  |  |
 Obese (≥30 kg/m2) | 744 | 66 (68.8 %) | 272 (60.2 %) | 324 (56.3 %) | 82 (38.9 %) |  |  |
Composite physical activity index—visit 1, mean (SD) | 1335 | 2.2 (1.4) | 2.7 (1.5) | 3.0 (1.5) | 3.3 (1.4) | <0.001 | 0.20 (<0.001) |
Average diastolic blood pressure (mmHg), mean (SD) | 1339 | 73.3 (9.3) | 73.4 (11.3) | 72.7 (10.3) | 72.1 (9.5) | 0.435 | −0.03 (0.238) |
Average systolic blood pressure (mmHg), mean (SD) | 1339 | 127.9 (19.4) | 129.0 (20.4) | 126.0 (18.6) | 125.1 (16.9) | 0.028 | −0.07 (0.008) |
Hypertensionc, n (% yes) | 1339 | 56 (58.3 %) | 258 (56.8 %) | 317 (54.9 %) | 107 (50.5 %) | 0.424 | § |
Hematocrit (%), mean (SD) | 1333 | 39.7 (4.2) | 40.6 (3.8) | 41.7 (3.7) | 41.9 (3.4) | <0.001 | 0.17 (<0.001) |
Total cholesterol (mg/dL), mean (SD) | 1337 | 213.8 (38.0) | 210.2 (40.5) | 213.6 (41.9) | 212.8 (42.5) | 0.586 | 0.02 (0.406) |
HDL (mg/dL), mean (SD) | 1336 | 44.7 (12.0) | 44.2 (14.4) | 41.0 (13.4) | 42.6 (14.2) | 0.001 | −0.09 (0.002) |
LDL (mg/dL), mean (SD) | 1279 | 138.8 (36.0) | 133.2 (35.0) | 135.5 (36.6) | 133.9 (37.5) | 0.504 | 0.01 (0.668) |
Triglycerides (mg/dL), mean (SD) | 1336 | 155.3 (82.2) | 166.2 (98.3) | 192.0 (132.0) | 182.7 (104.9) | <0.001 | 0.08 (0.004) |
Glucose (mg/dL), mean (SD) | 1339 | 184.2 (89.5) | 177.6 (76.6) | 171.6 (74.7) | 156.1 (62.3) | 0.002 | −0.11 (<0.001) |
Glycosylated hemoglobin (%), mean (SD) | 1339 | 7.8 (2.1) | 7.7 (2.1) | 7.4 (1.9) | 6.9 (1.6) | <0.001 | −0.14 (<0.001) |
Insulin use in the past 2 weeks, n (% yes) | 1339 | 16 (16.7 %) | 81 (17.8 %) | 70 (12.1 %) | 25 (11.8 %) | 0.039 | § |