Changes in insulin resistance mediate the associations between phthalate exposure and metabolic syndrome

Nai-Yueh Ko; Yuan-Ting C Lo; Po-Chin Huang; Yi-Chen Huang; Junn-Liang Chang; Han-Bin Huang

doi:10.1016/j.envres.2019.04.022

Changes in insulin resistance mediate the associations between phthalate exposure and metabolic syndrome

Environ Res. 2019 Aug:175:434-441. doi: 10.1016/j.envres.2019.04.022. Epub 2019 Apr 25.

Authors

Nai-Yueh Ko¹, Yuan-Ting C Lo¹, Po-Chin Huang², Yi-Chen Huang³, Junn-Liang Chang⁴, Han-Bin Huang⁵

Affiliations

¹ School of Public Health, National Defense Medical Center, Taipei, Taiwan.
² National Institute of Environmental Health Sciences, National Health Research Institutes, Miaoli and Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan.
³ Department of Nutrition, China Medical University, Taichung, Taiwan.
⁴ Department of Pathology & Laboratory Medicine, Taoyuan Armed Forces General Hospital, Taoyuan, Taiwan.
⁵ School of Public Health, National Defense Medical Center, Taipei, Taiwan. Electronic address: toly2000@gmail.com.

PMID: 31158561
DOI: 10.1016/j.envres.2019.04.022

Abstract

Background: Information on the relationships between phthalate exposure, insulin resistance, and metabolic syndrome (MetS) in younger adults is limited. It is still unclear whether changes in insulin resistance represent an intermediate biological mechanism linking phthalate exposure and MetS.

Objective: To investigate the associations between cumulative risk of phthalates (such as daily intake [DI] and hazard index [HI]), insulin resistance, and MetS in younger adults and to examine the mediating role of insulin resistance in the associations between phthalate exposure and MetS.

Methods: Urinary phthalate metabolite levels, insulin resistance (by using the Homeostatic Model Assessment of estimated Insulin Resistance [HOMA-IR]), and MetS status were determined in 435 military personnel in Taiwan. We estimated the DI of five phthalates: dimethyl phthalate (DMP), diethyl phthalate, dibutyl phthalate, benzyl butyl phthalate (BBzP), and di (2-ethylhexyl) phthalate and the HI based on urinary phthalate metabolite levels. Cross-sectional associations between DI and HI, HOMA-IR, and the indicators of MetS were explored using logistic regression models. Mediation analysis was conducted to assess the role of insulin resistance in the associations between phthalate exposure and MetS.

Results: Higher DI_DMP was associated with an increased odds of high HOMA-IR and MetS (odds ratio [OR], 1.686; 95% confidence interval [CI], 1.079-2.634 for high HOMA-IR; OR, 2.329; 95% CI, 1.263-4.295 for MetS). The mediation analysis indicated that 43% of the association between higher DI_DMP and MetS was mediated by HOMA-IR. Higher DI_BBzP and HI were associated with an increased odds of abdominal obesity (OR, 1.816; 95% CI, 1.180-2.797 for the high DI_BBzP group; OR, 1.700, 95% CI, 1.105-2.614 for the high HI groups).

Conclusions: Exposure to environmental phthalates may be positively associated with insulin resistance and MetS. Insulin resistance may mediate these associations between exposure to certain phthalates and MetS.

Keywords: Cumulative risk; Insulin resistance; Metabolic syndrome; Military; Phthalate.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Cross-Sectional Studies
Environmental Exposure / statistics & numerical data*
Environmental Pollutants*
Humans
Insulin Resistance*
Metabolic Syndrome / epidemiology*
Phthalic Acids*
Taiwan

Substances

Environmental Pollutants
Phthalic Acids
phthalic acid