Table 1. Characteristics of participants according to tongue coating categories.
| White | Light yellow | Yellow | P value | |
| (n = 468) | (n = 300) | (= 201) | ||
| Mean (SD) age, years | 56.3 (13.6) | 58.4 (12.3)* | 63.0 (11.0)* | <0.01 |
| Men, % | 25.2 | 32.7 | 49.3 | <0.01 |
| Body mass index, kg/m2 | 23.0 | 23.1 | 23.3 | 0.59 |
| Current drinker, % | 58.5 | 59.5 | 54.1 | 0.41 |
| Physical activity, METs h/day | 35.4 | 35.3 | 35.3 | 0.81 |
| Fasting serum glucose, mmol/dL | 5.17 | 5.19 | 5.18 | 0.87 |
| 1-h serum glucose, mmol/dL | 8.12 | 8.20 | 8.27 | 0.75 |
| 2-h serum glucose, mmol/L | 6.75 | 6.89 | 7.03 | 0.23 |
| HbA1c, % | 5.46 | 5.50 | 5.52 | 0.18 |
| Diabetes mellitus or prediabetes, % | 35.1 | 38.5 | 45.5* | 0.03 |
| Diabetes mellitus, % | 5.8 | 6.9 | 10.6 | 0.09 |
| Prediabetes, % | 29.3 | 31.6 | 34.9 | 0.34 |
| Mean CIE b* | 9.2 | 11.1* | 15.0* | <0.01 |
| Mean CIE h° | 24.3 | 32.8* | 46.0* | <0.01 |
CIE, Commission Internationale de l’Eclairage; HbA1c, glycosylated hemoglobin A1c; MET, metabolic equivalent; SD, standard deviation.
Values are adjusted for age and sex by the analysis of covariance. Age, CIE b*, CIE h° and sex values are shown as crude means and proportions.
*P < 0.05 as compared with white tongue coating (Dunnett’s test).