Limits...
Smoking and diabetes: is the association mediated by adiponectin, leptin, or C-reactive protein?

Hilawe EH, Yatsuya H, Li Y, Uemura M, Wang C, Chiang C, Toyoshima H, Tamakoshi K, Zhang Y, Kawazoe N, Aoyama A - J Epidemiol (2014)

Bottom Line: This study examined the possible mediating effects of adiponectin, leptin, and C-reactive protein (CRP) concentrations on the smoking-diabetes association.In contrast, neither the indirect effects of smoking on diabetes through leptin nor CRP levels were significant, as the corresponding BC 95% CIs included zero.In our analysis, adiponectin concentration appeared to partially mediate the effect of smoking on diabetes, while leptin and CRP levels did not.

View Article: PubMed Central - PubMed

Affiliation: Department of Public Health and Health Systems, Nagoya University Graduate School of Medicine.

ABSTRACT

Background: Although the association between cigarette smoking and risk of type 2 diabetes is well established, its mechanisms are yet to be clarified. This study examined the possible mediating effects of adiponectin, leptin, and C-reactive protein (CRP) concentrations on the smoking-diabetes association.

Methods: Between 2002 and 2011, we followed 3338 Japanese workers, aged 35-66 years, who were enrolled in the second Aichi workers' cohort study. We used multivariable-adjusted Cox regression models to determine the hazard ratios and respective 95% confidence intervals (CIs) of the association between smoking status and risk of diabetes. A multiple mediation model with bootstrapping was used to estimate the magnitude and the respective bias-corrected (BC) 95% CIs of the indirect effects of smoking on diabetes through the three biomarkers.

Results: Relative to never smokers, the risk of diabetes was significantly elevated in current (hazard ratio 1.75, 95% CI 1.25-2.46) and ex-smokers (hazard ratio 1.54, 95% CI 1.07-2.22). The indirect effects of smoking on diabetes through adiponectin levels were statistically significant among light (point estimate 0.033, BC 95% CI 0.005-0.082), moderate (point estimate 0.044, BC 95% CI 0.010-0.094), and heavy smokers (point estimate 0.054, BC 95% CI 0.013-0.113). In contrast, neither the indirect effects of smoking on diabetes through leptin nor CRP levels were significant, as the corresponding BC 95% CIs included zero.

Conclusions: In our analysis, adiponectin concentration appeared to partially mediate the effect of smoking on diabetes, while leptin and CRP levels did not.

Show MeSH

Related in: MedlinePlus

© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4310870&req=5

Mentions: Second, we conducted multiple mediation analysis using the PROCESS procedure for SPSS.41 Standard path-analytic approaches41–43 were followed to assess: 1) the effect of being an ex-(X1), light (X2), moderate (X3), or heavy (X4) smoker on DM incidence (Y) relative to never smokers (reference group)—c paths; 2) the differences between each smoking category and the reference group on the level of the proposed mediators (Ms), adiponectin (M1), leptin (M2), and CRP (M3)—a paths; and 3) the association between the Ms and Y while statistically equating the groups on average on X and the other potential mediators in the model—b paths (Figure 1). Coefficients for a paths were estimated using ordinary least-squares regression, whereas logistic regression was used for the coefficients of the b and c paths. All of these analyses were adjusted for the covariates included in the Cox model mentioned above. Unstandardized coefficients (β) with their standard errors (SE) are reported for each model. The c paths represent the total effects of Xs on Y relative to the reference group unadjusted for the group differences in Ms. These can be apportioned into the direct effects of being in one X group on Y relative to the reference group adjusted for the group differences in Ms (c′ paths) and the indirect effects through the Ms of being in one X group relative to the reference group on Y (estimated by the products of a and b paths—ab’s). Bias-corrected (BC) 95% CIs for the indirect effects were generated from 10 000 bootstrap samples, and statistical significance is indicated when the CI values do not cross zero. Bootstrapping is recommended for testing of indirect effects because it does not assume normality in sampling distribution.43


Smoking and diabetes: is the association mediated by adiponectin, leptin, or C-reactive protein?

Hilawe EH, Yatsuya H, Li Y, Uemura M, Wang C, Chiang C, Toyoshima H, Tamakoshi K, Zhang Y, Kawazoe N, Aoyama A - J Epidemiol (2014)

© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4310870&req=5

Mentions: Second, we conducted multiple mediation analysis using the PROCESS procedure for SPSS.41 Standard path-analytic approaches41–43 were followed to assess: 1) the effect of being an ex-(X1), light (X2), moderate (X3), or heavy (X4) smoker on DM incidence (Y) relative to never smokers (reference group)—c paths; 2) the differences between each smoking category and the reference group on the level of the proposed mediators (Ms), adiponectin (M1), leptin (M2), and CRP (M3)—a paths; and 3) the association between the Ms and Y while statistically equating the groups on average on X and the other potential mediators in the model—b paths (Figure 1). Coefficients for a paths were estimated using ordinary least-squares regression, whereas logistic regression was used for the coefficients of the b and c paths. All of these analyses were adjusted for the covariates included in the Cox model mentioned above. Unstandardized coefficients (β) with their standard errors (SE) are reported for each model. The c paths represent the total effects of Xs on Y relative to the reference group unadjusted for the group differences in Ms. These can be apportioned into the direct effects of being in one X group on Y relative to the reference group adjusted for the group differences in Ms (c′ paths) and the indirect effects through the Ms of being in one X group relative to the reference group on Y (estimated by the products of a and b paths—ab’s). Bias-corrected (BC) 95% CIs for the indirect effects were generated from 10 000 bootstrap samples, and statistical significance is indicated when the CI values do not cross zero. Bootstrapping is recommended for testing of indirect effects because it does not assume normality in sampling distribution.43

Bottom Line: This study examined the possible mediating effects of adiponectin, leptin, and C-reactive protein (CRP) concentrations on the smoking-diabetes association.In contrast, neither the indirect effects of smoking on diabetes through leptin nor CRP levels were significant, as the corresponding BC 95% CIs included zero.In our analysis, adiponectin concentration appeared to partially mediate the effect of smoking on diabetes, while leptin and CRP levels did not.

View Article: PubMed Central - PubMed

Affiliation: Department of Public Health and Health Systems, Nagoya University Graduate School of Medicine.

ABSTRACT

Background: Although the association between cigarette smoking and risk of type 2 diabetes is well established, its mechanisms are yet to be clarified. This study examined the possible mediating effects of adiponectin, leptin, and C-reactive protein (CRP) concentrations on the smoking-diabetes association.

Methods: Between 2002 and 2011, we followed 3338 Japanese workers, aged 35-66 years, who were enrolled in the second Aichi workers' cohort study. We used multivariable-adjusted Cox regression models to determine the hazard ratios and respective 95% confidence intervals (CIs) of the association between smoking status and risk of diabetes. A multiple mediation model with bootstrapping was used to estimate the magnitude and the respective bias-corrected (BC) 95% CIs of the indirect effects of smoking on diabetes through the three biomarkers.

Results: Relative to never smokers, the risk of diabetes was significantly elevated in current (hazard ratio 1.75, 95% CI 1.25-2.46) and ex-smokers (hazard ratio 1.54, 95% CI 1.07-2.22). The indirect effects of smoking on diabetes through adiponectin levels were statistically significant among light (point estimate 0.033, BC 95% CI 0.005-0.082), moderate (point estimate 0.044, BC 95% CI 0.010-0.094), and heavy smokers (point estimate 0.054, BC 95% CI 0.013-0.113). In contrast, neither the indirect effects of smoking on diabetes through leptin nor CRP levels were significant, as the corresponding BC 95% CIs included zero.

Conclusions: In our analysis, adiponectin concentration appeared to partially mediate the effect of smoking on diabetes, while leptin and CRP levels did not.

Show MeSH
Related in: MedlinePlus