# Obesity mediates the association of outdoor artificial light at night with type 2 diabetes mellitus

## TL;DR

Outdoor artificial light at night is linked to type 2 diabetes in rural Chinese adults, with obesity playing a key role in this relationship.

## Contribution

This study identifies obesity as a mediator linking artificial light at night to type 2 diabetes in rural populations.

## Key findings

- Outdoor artificial light at night is positively associated with type 2 diabetes and impaired glucose metabolism.
- Obesity-related measures like BMI and waist circumference mediate up to 36.41% of the association with diabetes.
- Certain groups, like the elderly and those with low income, are more vulnerable to artificial light's health effects.

## Abstract

This study aims to explore the association of outdoor ALAN exposure with T2DM and the mediating effects of obesity in Chinese rural adults. A total of 38,108 participants were recruited from the Henan Rural Cohort. ALAN was positively associated with T2DM and FPG, and negatively associated with insulin, HOMA-IR, as well as HOMA-β, and the effect sizes of per-quartile increase in ALAN were 1.24(1.19, 1.28), 0.14(0.13, 0.16), −1.19(-1.24, −1.14), −0.22(-0.25, −0.20), and −27.30(-29.11, −25.48), respectively. The elderly, men, current smokers, individuals with lower education or income, or physical inactivity were more vulnerable to ALAN-related adverse health effects. The associations of ALAN with T2DM and glucose metabolism were mediated by WC, BMI, WHtR, WHR, VFI, and BFP, with estimated mediation proportions of 36.41%, 25.14%, 33.98%, 22.33%, 24.39%, and 25.85%, respectively, for T2DM. These findings emphasize the need for targeted public health interventions for reducing ALAN-related adverse health effects in rural areas.

•ALAN was positively associated with T2DM and impaired glucose metabolism in rural areas•High-risk individuals with T2DM might benefit from controlling outdoor ALAN exposure•Obese indices appear to be key mediators of these associations, regardless of types•These findings provide evidence for promoting public health by reducing ALAN exposure

ALAN was positively associated with T2DM and impaired glucose metabolism in rural areas

High-risk individuals with T2DM might benefit from controlling outdoor ALAN exposure

Obese indices appear to be key mediators of these associations, regardless of types

These findings provide evidence for promoting public health by reducing ALAN exposure

Health sciences