November 14, 2022

expert reaction to study looking at exposure to outdoor artificial light at night and association with an increased risk of diabetes

A study published in Diabetologia looks at outdoor light at night and diabetes in Chinese adults.

Dr Gareth Nye, Senior Lecturer at the University of Chester, said:

“The press release itself doesn’t do enough to distinguish whether the body of work is concerning the type of diabetes – type 1 diabetes is based in ones genetics with type 2 being centred more in the lifestyle. Although the press release brings in many strands of research, the sheer volume of information here restricts its ability to portray the actual message of the study.

“This study utilises large datasets of people which usually allows for more confidence in our findings. It is unclear as to whether the population here was selected for this study or was retrospectively analysed which poses reliability issues, as does the selection of the representative sample as it is not discussed. Ultimately there is no confirmed evidence of this link and until further work is done to directly link light and diabetes in humans, the link will remain an association only.

“A number of studies have attempted to link artificial light and metabolic conditions like diabetes. Most theories centre around circadian rhythms which occur in our body. These internal clocks control many body functions, hormone functions and our metabolism. They also influence sleep patterns through disrupting the production of melatonin, which is the hormone responsible for healthy sleep.

“Healthy sleep is hugely important in preventing the development of diabetes. Studies have suggested that inconsistent sleep patterns have been linked to an increased risk of type 2 diabetes.

“This is the first to try and link outside levels of artificial light however.

“One issue with this study is that the areas with the highest outdoor artificial light levels are likely to be those in urban areas and bigger cities. It has been known for a long time now that living in a urbanised area increases your risk of obesity through increased access to high fat and convenience food, less physical activity levels due to transport links and less social activities. The authors also state this and the fact participants tended to be older.

“Obesity is heavily linked to type 2 diabetes therefore, the link between areas with more artificial light and diabetes may be found in the area itself rather than caused by the light.

“I would say that the conclusions drawn here are over speculation and somewhat disregard the previous evidence we have on the links between urban areas and diabetes.”

‘Outdoor light at night in relation to glucose homoeostasis and diabetes in Chinese adults: a national and cross-sectional study of 98,658 participants from 162 study sites’ by Ruizhi Zheng et al. was published in Diabetologia at 23:01 UK time Monday 14 November 2022.

DOI: 10.1007/s00125-022-05819-x

Declared interests

No reply to our request for DOIs was received.