Research has uncovered a surprising new risk factor for diabetes—rising outdoor temperatures from climate change.
Background: When the body is exposed to colder temperatures, insulin sensitivity (the ability to make efficient use of insulin) improves. That’s a good thing—a decline in insulin sensitivity, aka insulin resistance, is a major cause of type 2 diabetes. So researchers decided to explore whether there is a statistically strong connection between rising outdoor temperatures and the incidence of type 2 diabetes.
Study: Dutch researchers gathered data on average temperatures for each US state between 1996 and 2009 as well as the incidence of obesity (a major cause of increasingly deadly diabetes) and diabetes. Then they factored out the role of obesity and analyzed the relationship between average temperatures and new cases of diabetes.
Results: While diabetes incidence has been rising in general, it rose more dramatically in years that were hotter. Based on these spikes, the researchers calculated that if average annual temperatures in the US were to rise by 1.8°F (1°C), there would be an additional 100,000 new cases of diabetes each year. (In the next few decades, according to scientists, average temperatures are expected to rise in the US between 2°F and 4°F.)
While this kind of observational study can’t show cause and effect, the researchers point to metabolic research that adds credence to the connection. One emerging research area includes the different types of fat our bodies contain. Most body fat is white fat. It releases hormones and triggers other interactions that can result in insulin resistance, the major contributor to type 2 diabetes. But the body has a small amount of another kind of fat, too—brown fat. This kind of fat actually generates internal heat—it’s switched on in our bodies when external temperatures drop. So the more time our bodies are exposed to cooler temperatures, the more brown fat we create. When brown fat is switched on, it helps burn white fat.
The Bottom Line: While the researchers didn’t provide specific recommendations, there are some commonsense approaches you may want to try. When the weather’s cool or even cold, get outside—ideally, to exercise, since that’s a key way to protect against diabetes. When you’re inside, keep it cool (in the low-to-mid 60s, for example), especially at night, since cooler temperatures make it easier to sleep. That’s cool enough to activate brown fat. (To learn more, see the Bottom Line article, “Is Your Home Too Comfy for Your Health?”)
Planning retirement? You might want to research average temperatures as part of your planning and not automatically favor the warmest places.
