# Ecological assessment of extreme temperature and fine particulate matter (pm2.5) impact on diabetes service and outcomes in Thailand

## TL;DR

Extreme heat in Thailand is linked to reduced diabetes screening and worse blood sugar control, while air pollution (PM2.5) shows no significant impact.

## Contribution

This study is the first to analyze the impact of extreme temperature and PM2.5 on diabetes services and outcomes in Thailand using national data and ecological methods.

## Key findings

- Maximum temperatures between 31.6°C and 41.9°C were associated with reduced diabetes screening.
- Temperatures above 32.7°C were linked to lower proportions of patients achieving recommended blood sugar levels.
- PM2.5 levels showed no significant association with diabetes screening or blood glucose control.

## Abstract

Environmental changes, such as extreme heat and air pollution, are assumed to exacerbate chronic conditions like diabetes and increase demand for related health services. This study investigates how daily maximum temperature and air pollution affect diabetes service utilization in Thailand.

Using ecological analysis, national diabetes service data from the Thai Ministry of Public Health and ERA5 LAND satellite data (from 2018 to 2023) were examined. The data included 2-meter ambient temperature and particulate matter (PM2.5) concentrations, adjusted for health system variables, aggregated risk factors, the COVID-19 outbreak response, and spatiotemporal correlations. A generalized additive mixed model (GAMM) was employed to assess the effects of maximum temperature and PM2.5 on diabetes screening and the proportion of patients with controlled blood glucose.

The analysis revealed an annual average maximum temperature of 38.6 °C and an average PM2.5 concentration of 21.6 µg/m³. National diabetes screening was 87% of the target, and only 30% of diagnosed patients achieved the recommended blood glucose levels. Maximum temperature was found to non-linearly reduce diabetes screening, particularly between 31.6 °C and 41.9 °C, while no significant association was observed with PM2.5 levels. Temperatures above 32.7 °C were associated with lower proportions of patients achieving recommended blood sugar levels, while lower annual PM2.5 levels (16.4 to 18.8 µg/m³) had similar benefits.

Extreme heat was associated with reduced diabetes screening, while PM2.5 showed no significant effect. These findings highlight the need to adapt health service delivery to reduce the impact of heat stress on service utilization. Strategies such as shifting screening services closer to communities, promoting telemedicine, and strengthening the role of primary care and village health volunteers may help maintain access to care during periods of extreme temperature.

The online version contains supplementary material available at 10.1186/s12889-025-24003-5.