Does ‘brown fat’ explain a link between temperature, diabetes?

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ARE rising temperatures around the world also increasing the rates of diabetes? A new study from the Netherlands suggests that there may be a link between warming global temperatures and a higher prevalence of the disease, but not all experts are convinced.When the researchers analyzed average global temperatures and the rates of type 2 diabetes, they found that a 1.8-degree Fahrenheit (1 degree Celsius) increase in temperature was associated with an increase of 0.3 cases of diabetes per 1,000 people.
The new research may be interesting, but it shows only an association between rising temperatures and diabetes rates, said Dr. Christian Koch, a professor of endocrinology at the University of Mississippi Medical Center who was not involved in the new study. Although both temperatures and diabetes rates are rising, “there’s no causality” between the two, Koch added.
The study looked at the rates of type 2 diabetes in all 50 states, along with Guam, Puerto Rico and the U.S. Virgin Islands from 1996 to 2013. In addition, the researchers looked at data on the average temperatures in each state and territory for the same years.
Overall, the rate of people being diagnosed with type 2 diabetes was higher in warmer years, the researchers found. Data on worldwide type 2 diabetes rates was not available, the researchers noted. Instead, they used World Health Organization data on the rates of high blood sugar levels, a factor that is linked to diabetes.
For each 1.8-degree-Fahrenheit increase in average temperatures worldwide, the average rates of high blood sugar increased by 0.2 percent, the researchers found.
The findings suggest that, overall, the rates of diabetes in the United States and the rates of high blood sugar around the world increased with higher outdoor temperature worldwide, the researchers wrote in the study.
The potential link between rising temperatures and diabetes lies in a type of fat called brown adipose tissue, or brown fat, according to the study. Brown fat is metabolically active; it can break down smaller fat molecules to generate heat, the researchers wrote. Previous research has found that colder temperatures can activate brown fat and may lead to modest weight loss, according to the study. Additionally, in a small study published in the journal Nature Medicine in 2015, a group of researchers found that when patients with type 2 diabetes were exposed to moderately cold temperatures for 10 days, their insulin sensitivity improved.