
Exposure to natural light could help treat and stop type 2 diabetes, latest research being presented on the annual meeting of the European Association for the Study of Diabetes (EASD) in Hamburg, Germany (2-6 Oct) suggests.
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“The misalignment of our internal circadian clock with the demands of a 24/7 society is related to an increased incidence of metabolic diseases, including type 2 diabetes,” says Ivo Habets of Maastricht University, Maastricht, the Netherlands, who co-led the research. “Natural daylight is the strongest zeitgeber, or environmental cue, of the circadian clock, but most individuals are indoors throughout the day and so under constant artificial lighting.
“We were all in favour of whether increasing daytime exposure to natural light would improve blood sugar control in individuals with T2D.
“We also desired to know if it might affect their substrate metabolism or nutrient use. This normally follows a 24-hour rhythm, with the body switching from using carbohydrates as its source of energy throughout the day, to fat at night. We would previously shown that folks at higher risk of type 2 diabetes are less capable of make this switch and we wanted to seek out out if exposure to natural light would make the switch over easier in individuals who have already got diabetes.”
To explore this, Mr. Habets and colleagues within the Netherlands and Switzerland carried out a spread of metabolic tests on a gaggle of individuals with T2D once they were exposed to natural light and once they were exposed to artificial light and compared the outcomes. The 13 participants (average age:70 years, BMI: 30.1kg/m2, HbA1c: 6.1, fasting plasma glucose: 8.1mmol/L) stayed in research facilities, which allowed their light exposure, meal, and activity patterns to be tightly controlled.
They were exposed to 2 lighting conditions during office hours (8 am to five pm) in a randomized cross-over fashion: natural daylight from windows and artificial LED lighting. There was a niche of at the very least 4 weeks between the 2 interventions, each lasting 4.5 days.
Throughout the natural daylight intervention, the sunshine intensity was normally highest at 12:30 pm, with a median reading of 2453 lux. The unreal light was a continuing 300 lux.
Evenings were spent in dim light (lower than 5 lux), and the sleeping period (11 pm to 7 am) in darkness. The participants were supplied with standardized meals, meaning they ate the identical food in each interventions. Blood sugar levels were constantly recorded by monitors worn on the upper arm, and a spread of other tests were performed on the ultimate day and a half of every intervention.
On day 4, 24h substrate metabolism, resting energy expenditure, and respiratory exchange ratio (this provides a sign of whether fat or carbohydrates are getting used because the source of energy) were measured every five hours, and blood was taken to evaluate circulating metabolites. Core body temperature was measured for twenty-four hours. Substrate metabolism, resting energy expenditure, respiratory exchange ratio, and core body temperature all follow a 24-hour rhythm, and the researchers desired to see if this differed within the two conditions.
On day 5 (the ultimate half day), a fasted muscle biopsy was taken to evaluate clock gene expression – the activity of genes known to be involved within the circadian clock. A mixed meal test (MMT), a measure of insulin production, was then carried out.
Blood glucose levels were inside the conventional range (4.4-7.8 mmol/L) for longer throughout the natural daylight intervention than in the substitute light intervention (59% of the 4.5 days vs. 51%).
The respiratory exchange ratio was lower throughout the daylight intervention than during the substitute light intervention, indicating that the participants found it easier to modify from using carbohydrates to fat as an energy source when exposed to natural light.
Per1 and Cry1, genes that help control circadian rhythms, were more energetic in natural than artificial light.
Resting energy expenditure and core body temperature followed similar 24-hour patterns in each light conditions. Serum insulin levels measured throughout the MMT were similar in each light conditions, however the pattern of serum glucose and plasma free acids significantly differed between conditions.
The outcomes, particularly the higher blood sugar control throughout the natural light invention, suggest that exposure to natural daylight is useful to the metabolism and will help treat and stop type 2 diabetes and other metabolic conditions, comparable to obesity, says Mr Habets.
He adds: “Our research shows that the variety of light you might be exposed to matters on your metabolism. Should you work in an office with almost no exposure to natural light, it can impact your metabolism and your risk or control of type 2 diabetes, so attempt to get as much daylight as possible, and ideally, get outdoors when possible.
“Further research remains to be needed to find out the extent to which artificial light affects metabolism and the period of time that needs be spent in natural light or outdoors to compensate for this.”