Descriptive statistics of the study population
| Healthy control | Diabetes mellitus | P value | |
| Number of participants (F/M) | 267 (138/129) | 267 (138/129) | 1.000* |
| Age of participants (years) | 68.3±4.9 | 68.3±4.9 | 1.000* |
| Disease duration | – | 13.0±8.4 | – |
| Taking glucose-lowering agent (N) | – | 255 | – |
| Taking insulin (N) | – | 42 | – |
| Fasting blood glucose (mM) | 5.4 (0.7) | 8.9 (2.5) | <0.0001† |
| HbA1c (%) | 5.9 (0.5) | 7.8 (1.9) | <0.0001† |
| Urinary ketone bodies (negative/weak positive/positive) | 267 (265/2/0) | 252/13/2 | 0.002* |
| Urobilinogen (negative/weak positive/positive/strong positive) | 267 (265/0/1/1) | 267 (265/1/1/0) | 1.000* |
| Occupational exposure to organic solvent (N/Y) | 267 (259/8) | 267 (261/6) | 0.788 |
| Smoking (never/former and current) | 266 (204/62) | 267 (202/65) | 0.839* |
| BMI (<24 kg/m2/=24 kg/m2/>24 kg/m2) | 265 (136/107/22) | 266 (119/105/42) | 0.024* |
| Hypertension (negative/positive) | 267 (122/145) | 267 (86/181) | 0.002* |
| Coronary disease (negative/positive) | 267 (156/11) | 263 (236/27) | 0.007* |
| Pyrrole adduct (μM) | 5.9 (4.3) | 7.5 (5.4) | <0.0001† |
*Differences between groups were examined by the χ2 test.
†Differences between groups were examined by Mann-Whitney U test.
BMI, body mass index; HbA1c, glycated hemoglobin A1c.