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. Author manuscript; available in PMC: 2020 Apr 1.
Published in final edited form as: Environ Res. 2019 Jan 25;171:321–327. doi: 10.1016/j.envres.2019.01.035

Table 3.

Multivariable-adjusted associations [beta coefficients (95% CIs)] between toenail arsenic concentrations and levels of fasting glucose and insulin, HOMA-IR and HOMA beta cell function, as well as hs-CRP, the CARDIA study, 1987 to 2015 (n=3,666)a

Quintiles of toenail arsenic levels P for
linear
trend*
1
(lowest)		 2 3 4 5 (highest)
Arsenic, ppm <0.060 0.060–0.083 0.084–0.113 0.114–0.171 ≥0.172 NA
No. of participants 733 734 733 733 733 NA
No. of observations 3,237 3,303 3,255 3,213 3,127 NA
Ln (Glucose, mg/dL)b 0 (Ref.) −0.001 (−0.009, 0.007) 0.003 (−0.005, 0.012) 0.001 (−0.008, 0.009) 0.008 (−0.002, 0.017) 0.070
Ln (Insulin, μU/mL)b 0 (Ref.) −0.013 (−0.054, 0.028) −0.020 (−0.061, 0.021) 0.004 (−0.039, 0.046) 0.001 (−0.043, 0.045) 0.579
Ln (HOMA-IR)b 0 (Ref.) −0.012 (−0.057, 0.033) −0.009 (−0.054, 0.037) 0.008 (−0.039, 0.056) 0.015 (−0.034, 0.064) 0.280
Ln (HOMA-β)b 0 (Ref.) −0.009 (−0.048, 0.031) −0.027 (−0.067, 0.014) 0.002 (−0.039, 0.044) −0.013 (−0.055, 0.029) 0.810
Ln (hs-CRP, μg/mL)c 0 (Ref.) 0.014 (−0.082, 0.109) −0.032 (−0.128, 0.064) 0.007 (−0.093, 0.107) 0.002 (−0.099, 0.103) 0.934

Abbreviations: BMI, body mass index; CARDIA, Coronary Artery Risk Development in Young Adults; CI, Confidence interval; HOMA-β, homeostatic model assessment of beta cell function index, HOMA-IR, homeostatic model assessment of insulin resistance; hs-CRP, high sensitivity C-reactive protein; NA, not applicable.

a

All of the models were constructed by using generalized estimating equations.

b

Participants were excluded if they took antidiabetic medication, their fasting levels were <8 h, or they were pregnant women. The adjusted variables included age (continuous), sex, race (African American or Caucasian), study center, baseline glucose (continuous), baseline BMI (continuous), education (<12, 12, 12.1–15.9, 16, or ≥16 years), current smoking status (yes or no), alcohol consumption (0, 0.1–9.9, 10.0–19.9, or ≥20 g/day), physical activity (quintiles), family history of diabetes (yes or no), and measurement years (year 7, 10, 15, 20, 25, or 30).

c

The analysis was conducted with a sample size of 3,963. Participants were excluded if they had no baseline arsenic; had arthritis, asthma, or any other reported allergic diseases at baseline; did not have hs-CRP measured at any follow-up examination; or were pregnant women. The adjusted variables included age (continuous), sex, race (African American or Caucasian), study center, baseline BMI (continuous), education (<12, 12, 12.1–15.9, 16, or ≥16 years), current smoking status (yes or no), alcohol consumption (0, 0.1–9.9, 10.0–19.9, or ≥20 g/day), physical activity (quintiles), and measurement years (year 7, 15, 20, 25, or 30).

*

P for linear trend was examined by using medians of toenail arsenic across its quintiles in the models.