Table 2.

Multivariable-adjusted HRs (95% CIs) of diabetes by quintiles of toenail arsenic levels, the CARDIA study, 1987 to 2015 (n=4,102)^a

	Quintiles of toenail arsenic levels					P for linear trend*
	1 (lowest)	2	3	4	5 (highest)
Arsenic, ppm	<0.0593	0.0593–0.0827	0.0828–0.1119	0.1120–0.1691	≥0.1692
No. of participants	821	819	820	822	778	NA
No. of events	149	122	122	111	95	NA
Incidence rate,/1000 person years	8.96	7.22	7.32	6.70	5.93
Model 1b	1 (Ref.)	0.85 (0.67, 1.08)	0.93 (0.73, 1.18)	0.84 (0.65, 1.08)	0.77 (0.59, 1.01)	0.08
Model 2c	1 (Ref.)	0.95 (0.75, 1.22)	1.05 (0.82, 1.35)	1.00 (0.77, 1.29)	0.90 (0.69, 1.19)	0.48
Model 3d	1 (Ref.)	0.95 (0.75, 1.22)	1.04 (0.81, 1.33)	1.00 (0.77, 1.30)	0.96 (0.73, 1.27)	0.85

Abbreviations: BMI, body mass index; CARDIA, Coronary Artery Risk Development in Young Adults; CI, Confidence interval; HR, Hazard ratio; LCω₃PUFA, long-chain omega-3 polyunsaturated fatty acids; LDL, low-density lipoprotein; NA, not applicable.

^aAll models were constructed using the Cox proportional hazards regression analysis.

^bModel 1: adjustment for age (continuous), sex, race, study center, and baseline glucose levels (continuous).

^cModel 2: model 1 with additional adjustment for baseline BMI (continuous).

^dModel 3: model 2 with additional adjustment for 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 family history of diabetes (yes or no).

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