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21 March 2017

Researchers Assess Possible Link between Climate Change and Diabetes

Climate change doesn’t just affect the health of our planet, but also its animal and human populations. For years now, there have been widespread warnings from scientists concerning the impact on public health stemming from a rise in global temperatures, but the exact nature of this threat is not yet fully understood. Sure, we know some of dangers, but more research needs to be done in various fields.

Now, researchers are taking a close look at the possible link between climate change and one particular public health concern, namely Type 2 diabetes.

The study, published in the journal MBJ Open Diabetes Research & Care, spoke of how between 1996 and 2009, both outdoor temperatures and the prevalence of diabetes experienced a rise. The researchers hoped that their research may help to identify the association between the two, along with any direct causation.

“We were surprised though by the magnitude of the effect size,” said Lisanne Blauw, lead author of the study and researcher at Leiden University Medical Center.

“We calculated that a 1-degree Celsius rise in environmental temperature could account for more than 100,000 new diabetes cases per year in the USA alone. Future research into the effects of global warming on our health status is therefore of great importance.”

However, while the research certainly seems to suggest an association between climate and diabetes, there is little evidence of causation. Dr Adrian Vella, an endocrinologist known for his work on Type 2 diabetes at the Mayo Clinic, thinks other factors may be to blame.

“I think calorie consumption and weight are probably the biggest by a country mile,” said Dr Vella.

“I think the general message always should be that association studies do not actually imply causation.”

In conducting the new study, the researchers made use of data provided by the CDC’s Behavioral Risk Factor Surveillance System (BRFSS) to analyse the incidence of Type 2 diabetes in the United States and the territories of Puerto Rico, Guam, and the Virgin Islands. They also analysed mean annual temperature data from the National Centers for Environmental Protection, whilst fasting blood glucose levels and obesity data was provided by the World Health Organisation’s Global Health Observatory.

The researchers found that for each 1°C increase in outdoor temperature, diabetes incidence in the US also rose by approximately 4%. Meanwhile, the worldwide prevalence of glucose intolerance was found to rise by 0.17% per 1°C temperature rise.

The researchers wrote that, “To the best of our knowledge, this study is the first to assess the association of outdoor temperature with diabetes incidence and the prevalence of raised fasting blood glucose on a national and global level.”

The reason for this correlation remains unknown, but the researchers have suggested that it may involve brown adipose tissue, more commonly known as brown fat, which is activated by cooler temperatures.

“The function of brown fat tissue is to burn fat to generate heat, which is important to prevent a decline in body temperature during cold exposure. Therefore, we hypothesize that brown fat plays a role in the mechanism underlying the association between outdoor temperature and diabetes,” stated Ms Blauw.

 “In warmer climates, brown fat may be less activated, which may causally lead to insulin resistance and diabetes.”

Dr Vella, however, remains unconvinced.

“In humans, brown adipose tissue likely explains about 1% or 2% of energy expenditure in cold situations, and shivering explains far more, so it's an exaggeration,” he said.

“Between 1996 and 2009, I believe the environment has changed. Lots of things changed that might change diabetes incidence, right? The actual population composition changed a little bit. The caloric consumption of that population likely changed. We don't know about physical activity.”

In summary, while the new research suggests that there may in fact be an association between the rise in temperatures and the rise in prevalence of diabetes, further research is required before Ms Blauw and her team can assert any direct causation. For now, we can only wait on further studies in the field.

Sam Bonson

Sam is an aspiring novelist with a passion for fantasy and crime thrillers. He is currently working as a content writer, journalist & editor in an attempt to expand his horizons.