Table 2

Adjusted geometric means of HbA1c for quartiles of gamma-glutamyltransferase (GGT) by bilirubin and coffee consumption*
GGT† Trend Interaction
Stratification n Q1 (lowest) Q2 Q3 Q4 (highest) P P
Men
Bilirubin (mg/dL)
 Low (< 0.6) 2313 5.02 (4.97–5.07) 5.11 (5.06–5.16) 5.21 (5.16–5.26) 5.26 (5.20–5.31) < 10–9 0.72
 High (≥ 0.6) 2179 4.95 (4.89–5.00) 5.02 (4.97–5.07) 5.12 (5.07–5.17) 5.20 (5.15–5.25) < 10–10
Coffee (cups/day)
 < 1 1911 5.00 (4.95–5.06) 5.07 (5.02–5.13) 5.14 (5.09–5.20) 5.24 (5.18–5.29) < 10–6 0.64
 1–3 2036 4.96 (4.91–5.01) 5.05 (5.00–5.10) 5.16 (5.11–5.21) 5.20 (5.14–5.26) < 10–9
 ≥ 4 545 5.03 (4.94–5.12) 5.13 (5.03–5.23) 5.27 (5.17–5.37) 5.32 (5.19–5.45) < 10–3
Women
Bilirubin (mg/dL)
 Low (< 0.5) 2910 5.02 (4.99–5.05) 5.10 (5.07–5.13) 5.18 (5.15–5.21) 5.19 (5.16–5.22) < 10–16 0.22
 High (≥ 0.5) 3332 4.99 (4.96–5.02) 5.03 (5.01–5.06) 5.07 (5.04–5.10) 5.14 (5.11–5.17) < 10–12
Coffee (cups/day)
 < 1 2623 5.02 (4.99–5.06) 5.06 (5.03–5.10) 5.12 (5.09–5.15) 5.17 (5.14–5.20) < 10–9 0.86
 1–3 3081 4.99 (4.96–5.02) 5.07 (5.05–5.10) 5.13 (5.10–5.16) 5.15 (5.12–5.18) < 10–15
 ≥ 4 538 4.99 (4.93–5.06) 5.02 (4.95–5.09) 5.08 (5.01–5.15) 5.17 (5.09–5.24) < 10–3

In parentheses are 95% confidence intervals of geometric means.

* Adjusted for age, smoking, alcohol intake and body mass index by analysis of covariance.

† The first to the fourth quartile (Q1 to Q4) categories were ≤ 23, 24–35, 36–58 and ≥ 59 IU/L in men; and ≤ 15, 16–20, 21–29 and ≥ 30 IU/L in women.

‡ Ordinal values were assigned to GGT categories.

Wang et al.

Wang et al. BMC Endocrine Disorders 2012 12:24   doi:10.1186/1472-6823-12-24

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