London School of Hygiene & Tropical Medicine

New findings from researchers at the London School of Hygiene & Tropical Medicine show that higher outdoor temperatures are linked to an increased risk of hypoglycemia (dangerously low blood sugar levels) in adults living with type 1 diabetes.

The study found that the relationship between temperature and hypoglycaemia risk was non-linear, with the risk increasing more sharply at extreme temperatures. At 25°C, the risk of hypoglycaemia was around 30% higher compared to 13°C, which was the temperature associated with the lowest risk in this study. At 0°C the risk was about 10% higher.

The findings, published in Diabetes Care, were based on nearly 33 million glucose readings collected from continuous glucose monitors from 679 adults with type 1 diabetes between 2017-2024.

Continuous glucose monitors are now available to all people with type 1 diabetes under NHS care to monitor their glucose levels. This allowed the researchers to analyse a large volume of routinely collected glucose data. Daily outdoor temperatures were linked to individual glucose readings to assess how risk of hypoglycaemia changes with temperature.

Many people with type 1 diabetes report more frequent hypoglycaemia during hotter weather and there are biological explanations to explain this, however previous research on this topic is limited. This study is the first to link large scale, real world, individual level continuous glucose monitoring data with environmental temperature data to examine hypoglycaemia risk.

Harriet Daultrey, Honorary Clinical Lecturer at LSHTM, said: “Our findings are particularly important as climate change drives more frequent extreme temperature events and raises important questions about safe insulin dosing in people with type 1 diabetes during extreme temperatures, particularly in individuals already at higher risk of hypoglycaemia.”

Antonio Gasparrini, Professor of Biostatistics at LSHTM, said: ““This is the first study examining longitudinal readings from glucose monitoring devices to assess health risks associated with environmental stressors.

“It demonstrates how advances in technology and analytical methods can benefit patients, especially those more at risk to weather extremes that are becoming more frequent under climate change”.

The authors suggest that clearer guidance is needed on insulin adjustment during hotter weather and that the diabetes technologies, such as the automated insulin delivery systems, may need to incorporate ambient temperature to their algorithms.

Limitations

Temperature exposure was estimated using residential postcode, which may not reflect the temperature individuals experienced if they spent time indoors or travelling to different locations (such as work). The study population was based in Sussex, England, and findings may differ in other climates or populations.

Further research is needed to explore how these results apply in different settings and to understand how best to adjust insulin safely in response to temperature changes. 

Daultrey H et al. The Association Between Ambient Temperature and Hypoglycemia in People Living With Type 1 Diabetes: A Case Time Series Analysis Using Real-Time Continuous Glucose Monitoring. Diabetes Care, 2026. DOI: https://doi.org/10.2337/dc25-2383