More exposure to natural daylight may improve metabolic metrics in type 2 diabetes
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Key takeaways:
- Adults with type 2 diabetes spent more time with normal glucose levels when exposed to natural daylight vs. artificial light.
- Natural daylight was linked to a lower respiratory exchange ratio.
Spending more time in natural light may help improve metabolism for adults with type 2 diabetes, according to data from a small study presented at the European Association for the Study of Diabetes annual meeting.
“Our research shows that the type of light you are exposed to matters for your metabolism,” Ivo Habets, MSc, researcher in the department of nutrition and movement sciences at Maastricht University in the Netherlands, told Healio. “If you work in an office with almost no exposure to natural light, it will have an impact on your metabolism and your risk of or control of type 2 diabetes, so try to get as much daylight as possible and, ideally, get outdoors when you can.”
Researchers conducted a randomized crossover study with 13 adults with type 2 diabetes (mean age, 70 years). Participants were randomly assigned to a natural daylight intervention where natural light entered through windows between 8 a.m. and 5 p.m., or an artificial light intervention where participants were constantly exposed to artificial LED lighting. Evenings from 5 p.m. to 11 p.m. were spent in dim lighting and the sleeping period from 11 p.m. to 7 a.m. was spent in darkness. Each intervention lasted 4.5 days. After a 4-week washout period, participants crossed over to the opposite intervention for 4.5 days. Continuous glucose monitors were worn for the duration of the interventions.
On day 4, indirect calorimetry was performed to assess 24-hour substate metabolism and energy expenditure. Blood samples were collected to measure circulating metabolites. Core body temperature was measured for 24 hours with a telemetric pill. A fasting muscle biopsy was conducted on day 5 to assess clock gene expression, and a mixed meal tolerance test was performed following the fasting muscle biopsy.
Participants spent more time in a normal glucose range of 4.4 mmol/L to 7.8 mmol/L during the natural daylight intervention compared with artificial light (P = .01). Adults also had a lower respiratory exchange ratio throughout the 24-hour day cycle when exposed to natural daylight vs. artificial light (P = .028). The lower respiratory exchange ratio was particularly lower at 1 p.m. in the natural daylight group vs. artificial light. No differences in resting energy expenditure, plasma glucose, free fatty acids, triacylglycerol and core body temperature were observed between the interventions.
During the mixed meal test, no differences were observed in whole-body energy expenditure. However, respiratory exchange ratio was lower with the natural daylight intervention vs. artificial light (P = .04).
“As there were improvements in the time in target glucose range and respiratory exchange ratio, it is beneficial to evaluate and change the exposure to natural or artificial light of patients, as this might be an easy opportunity to have small improvements,” Habets said.
Habets added that the study was controlled and doesn’t reflect real-life exposure to light sources, necessitating the need for future studies. Additionally, he said future research should examine the mechanisms behind natural light and metabolic health benefits.
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Habets I, et al. Abstract 718. Presented at: European Association for the Study of Diabetes Annual Meeting; Oct. 2-6, 2023; Hamburg, Germany (hybrid meeting).
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