Nine million people suffer from diabetes, what risk factors are associated with it?

Exposure to outdoor artificial light at night is a ubiquitous environmental risk factor in modern society. Urban light pollution affects not only residents of large cities, but also residents of suburbs and remote areas such as forest parks hundreds of kilometers away from light sources. Although more than 80 percent of the world's population is exposed to light pollution at night, the issue has received little attention until recent years.

Under the 24-hour light-dark cycle in nature, most organisms, including mammals, have developed an endogenous circadian timing system to adapt to the regular alternation of light-dark phases. Exposure to artificial light at night may inhibit the nocturnal secretion of melatonin from the pineal gland, and animal experiments have found that light pollution can alter the circadian rhythms of insects, birds and other animals, leading to premature death and loss of biodiversity.

Additionally, studies have found that bedroom artificial light exposure is positively associated with the development of diabetes in the general older population. Diabetes is one of the serious public health problems in my country, and the onset and progression of diabetes are mainly attributed to behavioral and environmental risk factors. With the rapid development of urbanization, artificial lighting in cities in my country has greatly increased, and it is easier for people living in cities to shift from the 24-hour circadian rhythm of nature to the mode of working around the clock and being exposed to artificial light. Based on this, it is necessary to assess the extent of artificial light sources that cause diabetes or are associated with diabetes in order to implement effective prevention strategies.

In order to clarify the association between chronic exposure to outdoor artificial light and markers of glucose homeostasis and the prevalence of diabetes, a team from the Department of Endocrinology of Ruijin Hospital Affiliated to Shanghai Jiaotong University School of Medicine conducted a study. The higher the degree, the higher the incidence of diabetes. The research results were published on Diabetologia under the title "Outdoor light at night in relation to glucose homeostasis and diabetes in Chinese adults: a national and cross-sectional study of 98,658 participants from 162 study sites".

The study included data from 98,658 participants in the China Non-communicable Disease Surveillance Study, involving 162 research sites in different geographic regions of 31 provinces, autonomous regions, and municipalities directly under the central government. The average age of the participants was 42.7 years old. The BMI of the participants was evaluated, and their blood samples were collected to measure glycated hemoglobin, fasting and postprandial blood glucose levels, and further evaluate the participants' insulin resistance index, β-cell function, etc.

According to the average outdoor artificial light exposure level of each study site, the researchers divided it into five quintiles, and divided the participants into 5 groups, namely the 1st quantile group, the 2nd quantile group, and the 3rd quantile group. The median of the quantile array, the 4th quantile array, and the 5th quantile array, the outdoor artificial light exposure level at night is 1.0 nWcm-2sr-1 respectively

, 3.9 nW cm-2sr-1, 7.0 nW cm-2sr-1, 17.0 nW cm-2sr-1, 69.1 nW cm-2sr-1.

The researchers found that nighttime outdoor artificial light exposure levels were positively associated with participants' impaired blood sugar regulation, elevated blood sugar, and increased risk of diabetes. 7% increase. Compared with those in the 1st quartile, participants in the 5th quartile had a 28% increased risk of developing diabetes, an estimated 9 million people with diabetes attributable to artificial light exposure.

Based on this nationwide survey of Chinese adults, long-term exposure to residential outdoor artificial light was positively associated with blood glucose levels, insulin resistance, and diabetes prevalence, and negatively associated with β-cell function. These associations remained robust after adjusting for important diabetes risk factors. On average, there was one more person in 42 living with diabetes in areas with the highest exposure to artificial light compared to those living in the lowest quintile. The findings are important for assessing the impact of light pollution on the health of Chinese citizens.

Additionally, adverse effects of outdoor artificial light exposure on metabolic regulation and diseases have been found, including obesity, psychiatric disorders, and cancer. For example, in an analysis based on a prospective cohort of older adults in Hong Kong, a 60 nW cm -2 sr -1 increase in outdoor artificial light was associated with a 10% increase in CHD risk.

Exposure to artificial light is so damaging in humans because it may disrupt circadian rhythms, leading to changes in physiological activity and metabolic variables, including exercise, body temperature, food intake, lipid profile, insulin sensitivity, glucose Metabolism and plasma melatonin, glucocorticoids, and fatty acids. In addition, disturbances in the central clock caused by artificial light exposure lead to disturbed circadian rhythms in brain regions as well as disturbed interactions between different peripheral tissues.