Table 3.
Geometric means (95% CI) of glycemic and inflammatory parameters by categories of black tea consumptiona
| never or < 1 cup per week | 2-6 cups per week | ≥ 1 cup(s) per day | P trendb | |
|---|---|---|---|---|
| Fasting plasma glucose (mmol/L) | ||||
| Model-1c | 4.86 (4.83 - 4.89) | 4.81 (4.77 - 4.86) | 4.83 (4.80 - 4.86) | 0.144 |
| Model-2 | 4.78 (4.72 - 4.84) | 4.73 (4.66 - 4.80) | 4.75 (4.68 - 4.81) | 0.115 |
| HOMA-IR | ||||
| Model-1 | 1.55 (1.50 - 1.60) | 1.49 (1.42 - 1.57) | 1.61 (1.55 - 1.67) | 0.141 |
| Model-2 | 1.43 (1.34 - 1.52) | 1.35 (1.25 - 1.45) | 1.44 (1.35 - 1.54) | 0.579 |
| HOMA-beta | ||||
| Model-1 | 101.07 (98.18 - 104.04) | 105.48 (101.04 - 110.13) | 103.83 (100.59 - 107.17) | 0.169 |
| Model-2 | 103.34 (96.79 - 110.34) | 107.12 (99.69 - 115.10) | 105.49 (98.70 - 112.76) | 0.320 |
| HbA1c % | ||||
| Model-1 | 5.79 (5.76 - 5.82) | 5.75 (5.71 - 5.80) | 5.79 (5.76 - 5.82) | 0.987 |
| Model-2 | 5.73 (5.67 - 5.80) | 5.71 (5.64 - 5.78) | 5.72 (5.66 - 5.79) | 0.698 |
| Adiponectin: high-molecular weight (µg/ml) | ||||
| Model-1 | 1.05 (1.01 - 1.09) | 1.02 (0.96 - 1.08) | 1 (0.96 - 1.05) | 0.110 |
| Model-2 | 1.03 (0.94 - 1.12) | 1.01 (0.92 - 1.11) | 1 (0.92 - 1.09) | 0.327 |
| CRP (mg/L) | ||||
| Model-1 | 1.50 (1.41 - 1.59) | 1.46 (1.33 - 1.60) | 1.49 (1.40 - 1.59) | 0.929 |
| Model-2 | 1.34 (1.19 - 1.52) | 1.28 (1.12 - 1.46) | 1.32 (1.17 - 1.5) | 0.730 |
a HOMA-IR, homeostatic model assessment-insulin resistance; HOMA-beta, homeostatic model assessment-beta cell function; CRP, C-reactive protein. Numbers of participants differ across outcomes because participants with outlier values (response values > 4 SD from mean) were excluded. Numbers were as follows: fasting plasma glucose: 2130, 723, 1221 HOMA-IR: 2148, 727, 1233, HOMA-beta: 2143, 725, 1227, HbA1c: 1758, 587, 1008 HMW adiponectin: 2097, 705, 1215; and CRP: 2082, 700, 1213.
b P-values were obtained from multiple linear regression models with median cups of tea per week (0, 4,10.5) as predictors and log transformed parameters as dependant variables.
c Model-1: adjusted for age (years), sex and ethnicity (Chinese, Malay, Indian).
Model-2: adjusted for Model 1 covariates (above) and BMI (kg/m2), physical activity level (kcal/week), education level (primary, secondary, polytechnic/diploma and university), alcohol level (non-drinkers, < 1 serving/day, and ≥ 1 serving/day), cigarette smoking (never-smokers, ex-smokers, current smokers < 10 cigarettes/d, and current smokers ≥ 10 cigarettes/d), history of dyslipidemia (yes/no), history of hypertension (yes/no), and dietary confounders i.e. energy intake (kcal), fiber (per 1000 kcal), cholesterol (per 1000 kcal), PUFA (% energy), MUFA (% energy), SFA (% energy), coffee (never/rarely, < 1 cup per day, 1-2 cup(s) per day, ≥ 3 cups/day) and alternate teas (never or < 1 cup per week, 2-6 cups per week, ≥ 1 cup(s) per day). HOMA-beta models were further adjusted for HOMA-IR.