Does poorer blood sugar control cause a reduced capacity to lose heat in people with type 2 diabetes?

Poor blood sugar control could be associated with higher core body temperature and increased heart rate for physically active men with type 2 diabetes. The research published in Experimental Physiology found that while a common marker of long-term blood sugar control, haemoglobin A1c (also called glycated haemoglobin), was not associated with differences in the amount of heat lost from the body, heart rate rose by six beats per minute and core body temperature increased by 0.2°C with each percentage point rise in haemoglobin A1c (from 5.1% to 9.1%) in men with type 2 diabetes during cycling in a heated chamber.

People with type 2 diabetes can have a reduced ability to lose heat, which can heighten their risk of developing a heat-related injury during a heat stress. However, the cause of the reduced capacity to dissipate heat is not well understood. This health issue is becoming more relevant as countries around the globe experience more frequent and enduring temperature extremes as well as hotter average summer temperatures, such as the global heat waves of 2022.

Researchers from University of Ottawa, Canada sought to identify whether blood sugar control affects the body’s ability to lose heat during exercise in the heat. Although worse blood sugar control did not seem to impair whole-body heat loss, the association between chronically elevated blood sugar (indexed via haemoglobin A1c) with higher body core temperatures and heart rate could implicate its role in thermoregulation. Importantly, this effect did not appear to be related to the physical fitness of the participants.

The findings suggest that among people with type 2 diabetes, poor blood sugar control could lead to a greater risk of reaching dangerously high core body temperatures and greater strain on the heart during physical activity in the heat. However, more research is needed to confirm this link and understand why these impairments are observed even when heat loss is not compromised.

Reference:

Is poorer blood sugar control associated with a reduced capacity to lose heat during exercise in hot conditions for people with type 2 diabetes?; Experimental Physiology, DOI: 10.1113/EP090915.