Pollution and Temperature Variability Linked to Higher Glucose in European Cohorts

An observational study of 21,259 people across nine European cohorts found that greater exposure to air pollution, particularly PM10 particles, and increases in both temperature and temperature variability were associated with higher glycated haemoglobin (HbA1c), an indicator of average blood glucose over the preceding two to three months. The analysis included 5,464 participants from the GCAT|Genomes for Life cohort and focused on people without diabetes. It also identified interactions among the environmental exposures, while finding no consistent associations between the presence of green spaces and HbA1c levels.

Published in Environment International, the study was conducted as part of the European EXPANSE project, which examines how the urban exposome influences cardiometabolic and respiratory diseases. Researchers from the Swiss Tropical and Public Health Institute and the University of Basel led the work, with participation by the GCAT team at the Germans Trias i Pujol Research Institute in Spain. By evaluating air pollution, temperature, temperature variability and green spaces together, the investigators aimed to assess how different environmental conditions may relate to metabolic changes before diabetes develops. As an observational analysis, the study establishes statistical associations rather than showing that any of these exposures directly caused changes in blood glucose.

The analysis found that higher exposure to PM10 particles, higher temperatures and greater temperature variability were each associated with elevated HbA1c among participants who had not developed diabetes. The exposure effects were not independent: the model identified interactions among the environmental conditions. No consistent association was found between the presence of green spaces and HbA1c, although the investigators did not directly assess beta-cell function or insulin secretion. The authors suggested that inflammation and insulin resistance may be involved, describing them as possible mechanisms consistent with previous scientific evidence rather than mechanisms established by the study.

The researchers also evaluated different environmental scenarios using statistical models. In those estimates, improvements in air quality were associated with reductions in HbA1c, while certain temperature changes linked to climate change were associated with the opposite pattern. The combined context mattered: the same reduction in air pollution had a greater beneficial association with blood glucose under warmer temperature scenarios. These are model-based scenario estimates, not results from an intervention trial or measurements of what would necessarily occur in an individual person following an air-quality improvement.

GCAT co-author Natàlia Blay said the findings highlight the association between air pollution, temperature variability and HbA1c in people who have not developed diabetes. She said including temperature is particularly relevant in the climate-change context, where environmental exposures cannot be understood in isolation. GCAT principal investigator Sílvia Bonàs-Guarch said studies of the exposome can help investigate how environmental factors may contribute to metabolic changes before diabetes develops and may contribute to understanding the heterogeneous course of type 2 diabetes. The team is also working on approaches for assessing how genetic predisposition and environmental exposures may influence physiological processes such as pancreatic beta-cell insulin secretory capacity, but the reported study did not directly test that relationship.

Subject of Research: Environmental exposures and HbA1c in people without diabetes across nine European cohorts

Article Title: Air pollution and temperature variability are associated with higher blood glucose levels

Article References: Air pollution and temperature variability are associated with higher blood glucose levels. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: air pollution, PM10, blood glucose, HbA1c, temperature variability, climate change, urban exposome, type 2 diabetes, European cohorts, observational study, pollution, temperature