As you get ready to put up the holiday lights, here’s something to think about. A new, cross-sectional study in China found that in a sample of 98,658 adults, the prevalence of diabetes was 28% higher among people exposed to the greatest levels of artificial outdoor light compared to those who had the least exposure.
Researcher Yu Xu, Ph.D., of the Shanghai Jiaotong University School of Medicine, reported the findings in Diabetologia.
“The current study is the largest epidemiological study to test the hypothesis that increased exposure to outdoor LAN [light at night] is associated with a higher possibility of developing hyperglycemia, insulin resistance and diabetes,” Xu and his co-authors wrote.
According to MedPage Today, these findings may have global implications as the researchers suggested that more than 80% of the world’s population and 99% of Americans and Europeans live under light-polluted skies.
Exposure to artificial light at night may increase metabolic disease risk because our circadian rhythms are disrupted, said the researchers. This disruption leads to changes in many metabolic and physiological factors that can affect our insulin sensitivity, glucose metabolism, activity levels, and body temperature.
Previous studies have shown that exposure to artificial outdoor lights leads to obesity, psychiatric disorders and even cancer, says MedPage Today. Another study of older adults in Hong Kong found that people exposed to artificial light had an increased risk of hospitalization from coronary heart disease.
Xu and his colleagues used data from the U.S. Defense Meteorological Satellite Program that contained images of outdoor light at night, excluding light from the sun and moon, clouds, or other atmospheric lighting. Participants, who were part of the China Noncommunicable Disease Surveillance Study, were assigned a category of light exposure based on their geographic region. Diabetes was defined by the criteria of the American Diabetes Association. The mean age of the study subjects was approximately 43 years and nearly half were women.
The results were adjusted for age, sex, education, smoking status, alcohol use, physical activity, family history of diabetes, household income, urban versus rural location, medications, and body mass indices.
“Our findings contribute to the growing literature suggesting that LAN is detrimental to health and demonstrate that LAN may be a potential novel risk for diabetes,” Xu noted. “However, we advise caution against causal interpretation of the findings and call for further studies involving direct measurement of individual exposure to LAN.”