# Age-Specific Association Between Urinary Phthalate Metabolites and Diabetes Mellitus: Findings from the Korean National Environmental Health Survey Cycle 4 (2018–2020)

## TL;DR

This study found that the link between phthalate metabolites in urine and diabetes varies by age, with young and older adults showing stronger associations than middle-aged adults.

## Contribution

The study reveals age-specific differences in how phthalate exposure relates to diabetes, emphasizing the need for age-tailored prevention strategies.

## Key findings

- MnBP and MEP showed strong associations with diabetes in young and older adults.
- Middle-aged adults had more moderate associations between phthalate metabolites and diabetes.
- Age-specific patterns suggest life-course differences in metabolic vulnerability to phthalates.

## Abstract

What are the main findings?
Urinary phthalate metabolites showed distinct association with diabetes mellitus across age groups, indicating substantial age-related heterogeneity.MnBP and MEP emerged as key metabolites, with a strong association in young and older adults, whereas their effects in middle-aged adults were more moderate.

Urinary phthalate metabolites showed distinct association with diabetes mellitus across age groups, indicating substantial age-related heterogeneity.

MnBP and MEP emerged as key metabolites, with a strong association in young and older adults, whereas their effects in middle-aged adults were more moderate.

What are the implications of the main findings?
Age should be considered an effect modifier, rather than merely a covariate, in environmental diabetes research.Age-tailored exposure prevention and surveillance strategies may enhance the effectiveness of diabetes prevention efforts.

Age should be considered an effect modifier, rather than merely a covariate, in environmental diabetes research.

Age-tailored exposure prevention and surveillance strategies may enhance the effectiveness of diabetes prevention efforts.

Background/Objectives: Phthalates are encountered in everyday consumer and indoor environments, and their metabolites are commonly detected in urine. Although phthalate exposure has been linked to diabetes mellitus (DM), associations may vary by life stage. Therefore, we evaluated age-specific association between urinary phthalate metabolites and DM using nationally representative Korean data. Methods: We conducted a cross-sectional analysis of the Korean National Environmental Health Survey Cycle 4 (2018–2020). Adults aged ≥19 years with complete data were included. Eight urinary metabolites were evaluated. Metabolites were log-transformed, and those showing interaction were analyzed by tertiles. Complex survey-weighted logistic regression estimated odds ratios (95% confidence intervals) for DM, adjusting for demographic, socioeconomic, and health behavior factors. Analyses were stratified by age group. Results: Geometric mean (GM) concentrations among participants with DM varied significantly by age groups for several metabolites. Interaction analyses identified statistically significant effects for selected phthalate metabolites, including MnBP, MCPP, and MEP. In the age-stratified adjusted models, MnBP and MCPP were more strongly associated with DM in young adults, whereas the pattern for MEP appeared more evident in older adults, suggesting potential life-course differences in metabolic vulnerability. Conclusions: Associations between urinary phthalate metabolites and DM vary substantially by age, indicating life-course differences in exposure pathways and metabolic vulnerability. Age-specific prevention and surveillance strategies may improve environmental health interventions for DM.