• Posted November 26, 2025

Heat Waves Can Be Deadly for Seniors With Diabetes, Heart Disease

Heatwaves are increasing with climate change, and that could mean more deaths among older people with diabetes or heart disease, new research shows.

The study of U.S. veterans living in California found the largely male cohort vulnerable, especially if they were homeless or living in poorer neighborhoods.

Compared with cooler days, the typical California veteran living in a disadvantaged neighborhood faced a 44% higher odds of dying during a very hot day, the study found.

Often, these poorer neighborhoods are located in cities that create “urban heat islands” on sweltering days. 

In comparison, veterans living in better-off neighborhoods faced only a 12% higher odds of dying on a very hot day versus a cooler day, the research showed.

“Although this study was performed at the VA and only included veterans, we expect the findings to apply to non-Veterans as well,” said study lead author Dr. Evan Shannon. He’s assistant professor-in-residence at the David Geffen School of Medicine at the University of California Los Angeles.

According to the authors, the veterans in the study were at special risk from heat because many had metabolic illnesses such as diabetes and/or heart disease, and some heart medications can raise risks when temperatures soar. 

“Veterans with underlying risk factors for heart disease, including those with common conditions such as hypertension and diabetes, remain at risk of death during heat waves,” Shannon noted in a UCLA news release.

The study was published Nov. 25 in JAMA Network Open. Researchers combed through the VA electronic medical records of California veterans for the years 2016 through 2021.

They found 13,600 cases where veterans with cardiometabolic conditions (illnesses such as heart disease or diabetes) died during that time period. 

Those deaths were 10% to 14% more common overall on very hot days versus cooler days, the team noted. 

Housing (with the potential for air conditioning) made a big difference: Death risks on hot days rose by 25% among homeless veterans, compared to 12% for housed veterans, Shannon’s team found.

He and his colleagues say they are developing a “toolkit” that might be used by homeless veterans to stay safe.

“Given the projected increase in [extreme heat events] as global average temperatures rise, the VA and other integrated healthcare systems must develop heat preparedness and response plans to protect people from heat-related morbidity and mortality,” the researchers wrote.

More information

There’s more on protecting yourself in a heat wave at the American Lung Association.

SOURCE: University of California, Los Angeles, news release, Nov. 25, 2025