Clinical and demographic characteristics of the study population
| Variables | Discovery set | Validation set | ||||
| DM (n=46) | DR (n=46) | P value | DM (n=23) | DR (n=23) | P value | |
| Age, years | 55.3±11.1 | 58.1±10.5 | 0.205 | 53.0 (46.0, 55.0) | 55.0 (50.0, 65.0) | 0.073 |
| Male, # (%) | 24 (52) | 22 (48) | 0.677 | 14 (61) | 14 (61) | 1.000 |
| BMI, kg/m2 | 24.3±3.4 | 24.5±3.8 | 0.794 | 24.7±2.8 | 24.8±2.9 | 0.882 |
| FPG, mmol/L | 9.3±3.6 | 8.8±3.4 | 0.537 | 7.8 (7.0, 12.8) | 8.5 (6.4, 9.6) | 0.676 |
| HbA1c, % | 10.2±2.3 | 10.0±2.0 | 0.609 | 9.9±2.3 | 9.7±1.5 | 0.705 |
| HDL, mmol/L | 1.2±0.5 | 1.2±0.4 | 0.931 | 1.0±0.3 | 1.0±0.3 | 0.955 |
| LDL, mmol/L | 2.7±1.0 | 2.6±1.2 | 0.722 | 2.6±1.0 | 2.5±0.8 | 0.613 |
| TG, mmol/L | 1.6 (1.0, 2.2) | 1.4 (1.0, 1.8) | 0.234 | 1.6 (1.2, 2.0) | 1.6 (1.2, 2.1) | 0.684 |
| TC, mmol/L | 4.8±1.2 | 4.6±1.6 | 0.452 | 4.6±1.1 | 4.4±1.0 | 0.540 |
| DM duration, years | 7.5±6.5 | 11.7±6.4 | 0.002 | 7.8±6.1 | 11.3±7.3 | 0.083 |
| Therapy history, # (%) | <0.001 | 0.574 | ||||
| No | 17 (37) | 2 (4) | 3 (13) | 1 (4) | ||
| Yes | 25 (54) | 41 (89) | 17 (74) | 19 (83) | ||
| Unknown | 4 (9) | 3 (7) | 3 (13) | 3 (13) | ||
| Hypertension, # (%) | 0.524 | 0.200 | ||||
| No | 29 (63) | 24 (52) | 18 (78) | 14 (61) | ||
| Yes | 17 (37) | 22 (48) | 5 (22) | 9 (39) | ||
| Smoking habits, # (%) | 0.152 | 0.267 | ||||
| Non-smokers | 30 (65) | 25 (54) | 11 (48) | 11 (48) | ||
| Current smokers | 13 (28) | 13 (28) | 6 (26) | 8 (35) | ||
| Ex-smokers | 1 (2) | 7 (15) | 5 (22) | 1 (4) | ||
| Unavailable | 2 (4) | 1 (2) | 1 (4) | 3 (13) | ||
| Alcohol consumption, # (%) | 0.346 | 0.665 | ||||
| Non-drinkers | 21 (46) | 19 (41) | 12 (52) | 10 (44) | ||
| Current drinkers | 21 (46) | 19 (41) | 9 (39) | 8 (35) | ||
| Ex-drinkers | 2 (4) | 7 (15) | 1 (4) | 2 (9) | ||
| Unavailable | 2 (4) | 1 (2) | 1 (4) | 3 (13) | ||
Smoking habits were classified into three categories: (1) non-smokers, who never smoke; (2) ex-smokers, who had smoked before but quit smoking for at least 1 month; (3) current smokers, currently smoking over 3 months.
The alcohol consumption was also determined as three classes: (1) non-drinkers, who never drink; (2) ex-drinkers, who had drunk before but quit drinking for at least 1 month; (3) current drinkers, who drink for over 3 months currently.
Continuous data obeying normal or similar normal distribution were described as mean±SD, and the paired t-test was applied to compare the differences between the two groups. Otherwise, median (first quartile, third quartile) and Mann-Whitney U tests were used. Categorical data were presented as the number of cases (%), and the χ2 test was used to compare the differences between the cases and controls.
All the percentage presentations were kept as integer accuracy.
Therapy history is for diabetes medications.
BMI, body mass index; DM, diabetes mellitus; DR, diabetic retinopathy; FPG, fasting plasma glucose; HbA1c, glycated hemoglobin; HDL, high-density lipoprotein; LDL, low-density lipoprotein; TC, total cholesterol; TG, triglyceride.