The Unexpected Way Living In A Big City Is Linked To Diabetes

Living in a city can be exciting. With seemingly limitless spots to explore, people to meet, cultural attractions, and many opportunities for work, it's no wonder that more than 4 billion people around the world live in cities, per The World Bank. Depending on your values and lifestyle, you could live in any of the most vegan-friendly cities in the US, or any of the best cities to live in if you're outdoorsy. But, where we live and our environment can have an effect on our health, and living in a city is no exception.

While living in an urban environment can be a risk factor for certain ailments in itself, a new study published in Diabetologia found that exposure to outdoor artificial light at night, or LAN, could increase the risk of developing diabetes. While the exact cause of diabetes is unknown, it is defined as an excess of glucose in the bloodstream when the body cannot produce enough insulin, per the Mayo Clinic

Researchers estimate that more than 9 million cases of diabetes in China could be attributed to LAN, where "the onset and progression of the disease is largely governed by behavioral and environmental risk factors," per Diabetologia. In addition, the fact that so many people in the world live in towns and cities that suffer from light pollution — 99% in the United States alone and 83% internationally — illustrates that this is a worldwide problem and not an isolated one. In the U.S., for instance, more than 37 million people have diabetes, with an estimated 8.5 million people thought to be undiagnosed, per the CDC.

Regulating the body's circadian rhythms

The research published in Diabetologia, which was collected based on a sample group of close to 100,000 Chinese adults, found that those who lived in parts of China with high levels of artificial light pollution were 28% more likely to develop the disease than those who lived in its least light-polluted areas, per CNN. China's "rapid urbanization and economic growth" have contributed to what's said to be a "dramatic increase in urban lighting." However, the effects of light pollution on the body have been understudied, per Diabetologia. The study was conducted by taking blood samples of participants and correlating their exposure to LAN based on satellite imagery from the U.S. Defense Meteorological Satellite Program.

Per Medical News Today, our circadian rhythms are controlled by many things, but none more important than light. We're essentially synchronized with the Earth's natural 24-hour day to night cycle, and maintaining equilibrium with this rhythm keeps your body healthy, Healthline explains. LAN can disrupt the body's circadian rhythm through "round-the-clock working and leisure time" or other factors that permit chronic exposure, per Diabetologia. The study found that, as a result, LAN had an effect on blood-sugar control as well as insulin resistance, and subsequently, the development of diabetes. 

Exposure to LAN has also been studied as a risk factor to the development of breast cancer, and may also have an effect on the psychological, cardiovascular, and metabolic functions in the body.