Table 1. General characteristics of the retinal and skin study populations according to tertiles of retinal arteriolar %-dilation and skin %-hyperemia.
| Retinal study population | Skin study population | |||||||
|---|---|---|---|---|---|---|---|---|
| Characteristic | Tertile 1 of retinal arteriolar dilation (lowest) n = 662 | Tertile 2 of retinal arteriolar dilation n = 665 | Tertile 3 of retinal arteriolar dilation (highest) n = 664 | P for trend | Tertile 1 of skin hyperemia (lowest) n = 475 | Tertile 2 of skin hyperemia n = 476 | Tertile 3 of skin hyperemia (highest) n = 476 | P for trend |
| Range of retinal arteriolar %-dilation | -4.8 to 1.3 | 1.3 to 4.0 | 4.0 to 15.2 | - | - | - | - | |
| Range of skin %-hyperemia | - | - | - | - | 20.8 to 725.8 | 725.9 to 1286.6 | 1286.6 to 6763.6 | |
| Age (years) | 61.5±7.6 | 59.4±8.3 | 58.3±8.4 | <0.001 | 61.3±7.7 | 60.8±7.9 | 58.5±8.4 | <0.001 |
| Women | 289 (43.7) | 345 (51.9) | 337 (50.8) | 0.005 | 164 (34.5) | 212 (44.5) | 298 (62.6) | <0.001 |
| - Postmenopausal | 234 (84.5) | 256 (79.0) | 236 (72.0) | <0.001 | 126 (84.0) | 154 (79.4) | 198 (72.5) | <0.001 |
| - Hormone replacement therapy | 6 (0.9) | 6 (0.9) | 5 (0.8) | 0.942 | 2 (0.4) | 4 (0.8) | 9 (1.9) | 0.073 |
| Glucose metabolism status | <0.001 | <0.001 | ||||||
| - Normal glucose metabolism | 305 (46.1) | 388 (58.3) | 438 (66.0) | 216 (45.5) | 249 (52.3) | 298 (62.6) | ||
| - Prediabetes | 102 (15.4) | 92 (13.8) | 98 (14.8) | 74 (15.6) | 70 (14.7) | 78 (16.4) | ||
| - Type 2 diabetes | 242 (36.6) | 178 (26.8) | 125 (18.8) | 178 (37.5) | 146 (30.7) | 96 (20.2) | ||
| - Other types of diabetes | 13 (2.0) | 7 (1.1) | 3 (0.5) | 7 (1.5) | 11 (2.3) | 4 (0.8) | ||
| Type 2 diabetes duration (years) | 6.0 [3.0–13.0] | 5.0 [3.0–10.0] | 6.0 [3.0–13.0] | 0.223 | 5.5 [3.0–10.5] | 7.0 [3.0–13.0] | 6.0 [3.0–10.0] | 0.518 |
| Body mass index (kg/m2) | 27.4±4.4 | 26.7±4.7 | 26.5±4.2 | 0.001 | 26.9±4.1 | 27.2±4.4 | 26.7±4.6 | 0.220 |
| Weight (kg) | 80.1±15.5 | 78.4±16.2 | 78.2±15.4 | 0.047 | 79.7±14.7 | 80.3±15.4 | 77.2±14.7 | 0.003 |
| Height (cm) | 170.8±8.7 | 171.0±9.0 | 171.4±8.8 | 0.399 | 171.9±8.5 | 171.5±8.7 | 169.9±8.7 | 0.001 |
| Waist circumference (cm) | ||||||||
| - Men | 102.6±12.3 | 100.6±12.2 | 99.9±10.8 | 0.007 | 101.4±11.9 | 101.7±11.7 | 99.2±11.1 | 0.063 |
| - Women | 89.9±12.2 | 89.2±13.1 | 88.0±12.2 | 0.162 | 88.8±12.2 | 90.6±12.6 | 90.4±13.3 | 0.329 |
| History of cardiovascular disease | 132 (20.2) | 101 (15.4) | 73 (11.1) | <0.001 | 91 (19.4) | 86 (18.4) | 72 (15.3) | 0.227 |
| Office SBP (mmHg) | 136.7±18.0 | 134.0±18.4 | 134.3±17.5 | 0.013 | 136.6±17.4 | 136.0±18.6 | 134.6±18.4 | 0.210 |
| Office DBP (mmHg) | 75.7±9.8 | 76.2±10.3 | 76.9±9.6 | 0.070 | 76.3±9.4 | 76.4±9.8 | 76.7±9.8 | 0.770 |
| Ambulatory 24-h SBP (mmHg) | 119.6±11.5 | 119.0±12.4 | 118.9±10.9 | 0.477 | 121.8±11.9 | 120.0±11.9 | 117.5±10.8 | <0.001 |
| Ambulatory 24-h DBP (mmHg) | 72.8±7.1 | 73.6±7.5 | 74.1±6.8 | 0.002 | 74.0±7.1 | 73.5±7.0 | 73.4±6.5 | 0.375 |
| Ambulatory 24-h PP (mmHg) | 46.8±8.9 | 45.4±8.8 | 44.7±7.7 | <0.001 | 47.8±9.1 | 46.6±9.0 | 44.1±8.1 | <0.001 |
| Ambulatory 24-h MAP (mmHg) | 88.4±7.8 | 88.8±8.5 | 89.0±7.5 | 0.305 | 89.9±7.9 | 89.0±7.9 | 88.1±7.2 | 0.002 |
| Smoking | ||||||||
| - Never / former / current | 198/386/78 | 248/328/89 | 253/337/74 | 0.005 | 152/244/79 | 137/286/53 | 180/251/45 | <0.001 |
| - % (never / former / current) | 29.9/58.3/11.8 | 37.3/49.3/13.4 | 38.1/50.8/11.1 | 0.005 | 32.0/51.4/16.6 | 28.8/60.1/11.1 | 37.8/52.7/9.5 | <0.001 |
| Pack-years of smoking | 4.6 [0.0–20.0] | 1.0 [0.0–17.2] | 0.7 [0.0–13.0] | 0.001 | 4.6 [0.0–22.2] | 6.0 [0.0–22.5] | 1.3 [0.0–14.0] | <0.001 |
| Fasting glucose (mmol/l) | 6.4±2.0 | 6.0±1.6 | 5.8±1.3 | <0.001 | 6.4±1.9 | 6.1±1.6 | 5.8±1.3 | <0.001 |
| 2-h postload glucose (mmol/l) | 8.6±4.6 | 7.9±4.2 | 7.3±3.8 | <0.001 | 8.8±4.7 | 8.2±4.2 | 7.3±4.0 | <0.001 |
| HbA1c (%) | 6.1±1.1 | 5.8±0.9 | 5.7±0.7 | <0.001 | 6.1±1.1 | 6.0±0.9 | 5.8±0.8 | <0.001 |
| HbA1c (mmol/mol) | 43.3±11.8 | 40.3±9.5 | 38.8±7.9 | <0.001 | 43.7±11.7 | 41.8±9.5 | 39.9±8.7 | <0.001 |
| Total-to-HDL cholesterol ratio | 3.5±1.1 | 3.6±1.2 | 3.6±1.2 | 0.168 | 3.8±1.1 | 3.7±1.2 | 3.6±1.1 | 0.181 |
| Total cholesterol (mmol/l) | 5.0±1.2 | 5.3±1.2 | 5.4±1.1 | <0.001 | 5.1±1.1 | 5.2±1.2 | 5.4±1.2 | <0.001 |
| HDL cholesterol (mmol/l) | 1.5±0.5 | 1.6±0.5 | 1.6±0.5 | 0.019 | 1.4±0.5 | 1.5±0.5 | 1.6±0.5 | <0.001 |
| LDL cholesterol (mmol/l) | 2.9±1.0 | 3.1±1.0 | 3.2±1.0 | <0.001 | 2.9±1.0 | 3.1±1.1 | 3.3±1.1 | <0.001 |
| Triglycerides (mmol/l) | 1.5±0.8 | 1.5±0.9 | 1.3±0.7 | 0.001 | 1.5±0.8 | 1.5±1.0 | 1.3±0.8 | <0.001 |
| Antihypertensive medication use | 305 (46.1) | 257 (38.6) | 198 (29.8) | <0.001 | 219 (46.1) | 211 (44.3) | 163 (34.2) | <0.001 |
| Lipid-modifying medication use | 309 (46.7) | 221 (33.2) | 176 (26.5) | <0.001 | 209 (44.0) | 202 (42.4) | 146 (30.7) | <0.001 |
| Diabetes medication use | ||||||||
| - Any type | 205 (31.0) | 143 (21.5) | 98 (14.8) | <0.001 | 147 (30.9) | 127 (26.7) | 77 (16.2) | <0.001 |
| - Insulin | 71 (10.7) | 37 (5.6) | 24 (3.6) | <0.001 | 42 (8.8) | 41 (8.6) | 22 (4.6) | 0.020 |
| - Oral glucose-lowering medication | 180 (27.2) | 131 (19.7) | 87 (13.1) | <0.001 | 132 (27.8) | 112 (23.5) | 67 (14.1) | <0.001 |
| eGFR (ml/min/1.73m2) | 86.7±15.8 | 88.5±14.4 | 89.5±13.5 | 0.001 | 87.4±14.7 | 88.0±14.8 | 89.7±13.8 | 0.044 |
| eGFR<60 ml/min/1.73m2 | 45 (6.8) | 25 (3.8) | 15 (2.3) | <0.001 | 15 (3.2) | 19 (4.0) | 17 (3.6) | 0.780 |
| (Micro)albuminuria* | 78 (11.8) | 42 (6.4) | 43 (6.5) | <0.001 | 50 (10.6) | 42 (8.9) | 25 (5.3) | 0.011 |
| Retinopathy | 20 (3.1) | 10 (1.6) | 2 (0.3) | <0.001 | 7 (1.6) | 11 (2.6) | 3 (0.7) | 0.099 |
| Baseline arteriolar diameter (MU) | 119.4±15.0 | 115.3±15.5 | 111.6±15.2 | <0.001 | - | - | - | - |
| Arteriolar average dilation (%) | ||||||||
| - Mean±SD | 0.2±0.9 | 2.6±0.8 | 6.3±1.8 | <0.001 | - | - | - | - |
| - Median (interquartile range) | 0.4 [-0.2–0.8] | 2.6 [1.9–3.3] | 5.9 [4.9–7.2] | <0.001 | - | - | - | - |
| Baseline skin blood flow (PU) | - | - | - | - | 15.5±8.5 | 9.9±4.0 | 7.7±2.6 | <0.001 |
| Skin hyperemic response (%) | ||||||||
| - Mean±SD | - | - | - | - | 418.2±191.3 | 992.2±158.9 | 1976.8±715.6 | <0.001 |
| - Median (interquartile range) | - | - | - | - | 423.5 [256.1–586.2] | 1002.0 [852.4–1119.0] | 1757.7 [1508.7–2196.2] | <0.001 |
Data are reported as mean±SD, median [interquartile range], or number (percentages %) as appropriate. SBP, systolic blood pressure; DBP, diastolic blood pressure; MAP, mean arterial pressure; PP, pulse pressure; HbA1c, glycated hemoglobin A1c; HDL, high-density lipoprotein; LDL, low-density lipoprotein; eGFR, estimated glomerular filtration rate; MU, measurement units; PU, perfusion units; SD, standard deviation. P for trend as determined with use of one-way ANOVA for continuous variables and χ2-test for categorical variables.
* = (Micro)albuminuria was defined as a urinary albumin excretion of >30 mg per 24 hours.