Table 2

Geometric means (95% CI) of glycemic and inflammatory parameters by categories of coffee consumptiona

Never or rarely

< 1 cup/day

1-2 cup(s)/day

≥ 3 cups/day

P trendb


Fasting plasma glucose (mmol/L)

Model-1c

4.83 (4.79 - 4.86)

4.81 (4.75 - 4.86)

4.86 (4.83 - 4.89)

4.82 (4.76 - 4.88)

0.554

Model-2

4.76 (4.69 - 4.82)

4.73 (4.66 - 4.81)

4.78 (4.72 - 4.84)

4.74 (4.66 - 4.82)

0.916

HOMA-IR

Model-1

1.58 (1.52 - 1.65)

1.54 (1.44 - 1.64)

1.56 (1.51 - 1.62)

1.53 (1.42 - 1.64)

0.449

Model-2

1.47 (1.38 - 1.57)

1.41 (1.30 - 1.52)

1.41 (1.32 - 1.50)

1.34 (1.23 - 1.46)

0.007

Model-3d

1.43 (1.34 - 1.53)

1.36 (1.26 - 1.47)

1.36 (1.28 - 1.45)

1.32 (1.22 - 1.44)

0.021

HOMA-beta

Model-1

104.68 (101.2 - 108.28)

105.57 (100.27 - 111.15)

100.54 (97.81 - 103.35)

106.42 (100.24 - 112.98)

0.715

Model-2

106.24 (99.34 - 113.63)

106.15 (98.43 - 114.47)

101.9 (95.64 - 108.57)

107.02 (98.29 - 116.51)

0.591

HbA1c %

Model-1

5.79 (5.76 - 5.83)

5.72 (5.67 - 5.78)

5.78 (5.76 - 5.81)

5.8 (5.74 - 5.86)

0.567

Model-2

5.75 (5.69 - 5.82)

5.69 (5.62 - 5.76)

5.72 (5.66 - 5.78)

5.72 (5.64 - 5.8)

0.375

Adiponectin (high molecular weight) µg/ml

Model-1

1.03 (0.98 - 1.08)

1.04 (0.97 - 1.12)

1.02 (0.98 - 1.06)

1.03 (0.95 - 1.12)

0.953

Model-2

0.99 (0.91 - 1.08)

1.02 (0.92 - 1.12)

1.00 (0.92 - 1.08)

1.04 (0.93 - 1.16)

0.347

CRP (mg/L)

Model-1

1.42 (1.32 - 1.52)

1.59 (1.43 - 1.77)

1.49 (1.41 - 1.58)

1.59 (1.41 - 1.81)

0.139

Model-2

1.31 (1.16 - 1.49)

1.43 (1.25 - 1.65)

1.28 (1.14 - 1.44)

1.23 (1.05 - 1.44)

0.185


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. These numbers across the 4 categories of coffee consumption are fasting plasma glucose: 1187,461,2084,342; HOMA-IR: 1195,468,2102,343; HOMA-beta: 1187, 468, 2097, 343; HbA1c: 967, 388, 1717, 281; HMW adiponectin: 1176, 452, 2056, 333 and CRP: 1168, 450, 2046, 331.

b P-values were obtained from multiple linear regression models with median cups of coffee per week (0, 4,10.5 and 28) 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), green, black, Oolong tea (never/< 1cup per week, 2-6 cups per week, ≥ 1 cup(s) per day). HOMA-beta models were further adjusted for HOMA-IR.

d Model-3 was further adjusted for CRP and adiponectin

Rebello et al. Nutrition Journal 2011 10:61   doi:10.1186/1475-2891-10-61

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