How daylight may help people with type 2 diabetes regain metabolic balance

From thehansindia.com

A growing body of research is reshaping the way we understand health, and the latest findings suggest that something as simple and accessible as daylight could play a meaningful role in managing type 2 diabetes. A new study indicates that exposure to natural light can improve metabolic health and help people with the condition achieve better blood sugar control, highlighting the powerful link between light, the body’s internal clock, and metabolism.

Conducted by researchers from the University of Geneva (UNIGE) in Switzerland and Maastricht University in the Netherlands, the study offers the first direct evidence that natural daylight has measurable benefits for people living with type 2 diabetes. The findings were published in the scientific journal Cell Metabolism. 

Daylight and blood sugar control

The study revealed that individuals exposed to natural light spent more hours each day with blood glucose levels within the normal range. Not only were their glucose levels better regulated, but they also showed less variability — a key factor in managing diabetes and preventing long-term complications. Compared to artificial lighting, daylight appeared to provide a more stable metabolic environment, helping the body process glucose more efficiently. This suggests that beyond diet and medication, environmental factors like light exposure may significantly influence glycaemic control. 

The role of the body clock 

For years, scientists have known that the disruption of circadian rhythms — the body’s internal 24-hour clock — is closely linked to metabolic disorders. Charna Dibner, associate professor at UNIGE and one of the study’s authors, explained that circadian misalignment plays a major role in the rising prevalence of metabolic diseases, particularly in Western societies.

Natural light acts as the strongest regulator of the circadian rhythm. By aligning the body’s internal clock more accurately with the day-night cycle, daylight helps coordinate metabolic processes, including insulin sensitivity and glucose metabolism. “This coordination between the central clock in the brain and the clocks in peripheral organs may be key to improved blood sugar regulation,” Dibner noted. 

Inside the study 

To explore this relationship in detail, the research team recruited 13 volunteers aged 65 and above, all diagnosed with type 2 diabetes. Each participant spent 4.5 days in specially designed living environments. One setting was illuminated primarily by natural daylight entering through large windows, while the other relied on artificial lighting. After a washout period of at least four weeks, the volunteers returned for a second session, switching light environments. This crossover design allowed researchers to directly compare how the same individuals responded to different lighting conditions.

What the scientists measured 

To understand the biological mechanisms behind the changes, the researchers collected blood and muscle samples before, during, and after each lighting exposure. They examined molecular clocks in skeletal muscle cells, along with lipids, metabolites, and gene transcripts in the blood. The analysis showed that natural light positively influenced the regulation of these molecular clocks, which play a crucial role in metabolic function. The results also pointed to improved fat oxidative metabolism, meaning the body was better able to burn fat for energy.

Beyond blood sugar: Sleep and hormones 

Another notable finding was the impact of daylight on melatonin, the hormone responsible for regulating sleep. Participants exposed to natural light had slightly higher melatonin levels in the evening, suggesting improved sleep signalling.

Better sleep quality and timing are closely linked to metabolic health, reinforcing the idea that daylight supports the body in multiple, interconnected ways. 

A simple, promising intervention 

Taken together, the findings strongly indicate that natural light influences both metabolism and the internal clock. This could explain the improved blood sugar regulation and metabolic coordination observed in the study. 

While larger studies are needed to confirm these results, the research opens the door to new, non-invasive strategies for managing type 2 diabetes. Something as straightforward as increasing daily exposure to daylight — at home, work, or during outdoor activity — may one day become a valuable complement to existing treatments.

In an era of artificial lighting and indoor lifestyles, the study serves as a reminder that aligning with nature’s rhythms could be a powerful tool for better health.

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Could resetting our internal clocks help control diabetes?

From innovations-report.com

Researchers from UNIGE and HUG were able to demonstrate the link between disturbances of the circadian clocks in pancreatic cells and type 2 diabetes, then to correct these disturbances

The circadian clock system (from Latin "circa diem", about a day) allows the organisms to anticipate periodical changes of geophysical time, and to adjust to these changes. Nearly all the cells in our body comprise molecular clocks that regulate and synchronize metabolic functions to a 24-hour cycle of day-night changes.

Today, increasing evidence show that disturbances in our internal clocks stemming from frequent time zone changes, irregular working schedules or ageing, have a significant impact on the development of metabolic diseases in human beings, including type-2 diabetes.

Such disturbances seem to prevent the proper functioning of the cells in the pancreatic islet that secrete insulin and glucagon, the hormones that regulate blood sugar levels. By comparing the pancreatic cells of type 2 diabetic human donors with those of healthy people, researchers at the University of Geneva (UNIGE) and at the University Hospitals of Geneva (HUG), Switzerland, were able to demonstrate, for the first time, that the pancreatic islet cells derived from the Type 2 Diabetic human donors bear compromised circadian oscillators.

A Langerhans Islet with insulin-producing cells (in green), and glucagon-producing cells (in red). Cell nuclei in blue.
Credit: © UNIGE , Dibner Lab

The disruption of the circadian clocks was concomitant with the perturbation of hormone secretion. Moreover, using clock modulator molecule dubbed Nobiletin, extracted from lemon peel, the researchers succeeded in "repairing" the disrupted cellular clocks and in partial restoring of the islet cell function. These results, published in the Proceedings of the National Academy of Sciences of the United States, provide a first insight into innovative approach for diabetes care.

Two years ago, the team led by Charna Dibner, Principle Investigator in the Departments of Medicine and of Cell Physiology and Metabolism, and Diabetes Centre at UNIGE Faculty of Medicine, and at HUG, has already shown that in rodents the perturbation of pancreatic cellular clocks led to disrupted insulin and glucagon secretion, thus promoting the onset of diabetes. But what is the situation in human beings?

"We had also previously observed that if the clocks of human pancreatic cells were artificially disrupted in the cellular culture in vitro, secretion of the key islet hormones - insulin and glucagon - was compromised,» says Volodymyr Petrenko, a researcher in Dr. Dibner's lab and the first author of these publications. Hence our next step, that we report here, was to unravel whether the circadian rhythms were perturbed in human pancreatic islets in type 2 diabetes, and, if so, how would this perturbation affect the islet function."

Using combined bioluminescence-fluorescence time-lapse microscopy, a technology that allows tracking the molecular clock activity in living cells very precisely over time, the scientists compared the behaviour of pancreatic cell of type-2 diabetic donors and those of healthy subjects throughout the day.

"The verdict is indisputable", says Charna Dibner. The biological rhythms of the islet cells in type-2 diabetes exhibit both reduced amplitudes of circadian oscillations and poor synchronization capacity. «As a result, hormone secretion is no longer coordinated. Moreover, the defects in temporal coordination of insulin and glucagon secretion observed in patients with type-2 diabetes were comparable to those measured in healthy islet cells with artificially-disrupted circadian clock."

It's all in the timing!

Circadian clocks represent the daily cycles governing the various cellular functions. There are several interlocking levels of synchronization of these clocks, the main one being light, which in particular regulates the central clock located in the cerebral hypothalamus. Like a conductor in the orchestra, it regulates peripheral clocks present in organs and cells. The latter are therefore partly centrally regulated, but function differently in each organ, and even in each cell, depending on their functions.

"Pancreatic cells are also subject to the rhythm of fasting and food intake, and to a tight hormonal regulation", says Charna Dibner. "Coordinating all levels of regulation therefore allows the optimization of metabolic functions. Clocks deregulation in pancreatic islet leads to a compromised function: they are not anymore anticipating food-derived signals. Indeed, if you eat the same food but at night rather than during the day, you may gain weight much faster, due to a suboptimal response of your metabolism."

Setting the right time again

Step two of their research: the Geneva scientists used Nobiletin, a small clock modulator molecule - a natural ingredient of lemon peel whose impact on circadian clocks has been recently discovered - in order to resynchronize the clocks. "By acting on one of the core-clock components, it resets efficiently the amplitude of the oscillations in the human islets" says Volodymyr Petrenko. "And as soon as we got the clocks back in sync, we also observed an improvement in insulin secretion."

"This is the first proof of principle that repairing compromised circadian clocks may help improving the function of the pancreatic islet hormone secretion", says Charna Dibner. "We will continue by exploring this repair mechanism in vivo, first in animal models. Our society experiences epidemic growth in metabolic diseases, concomitant with shifted working and eating schedules, and lack of sleep. By re-synchronizing the perturbed molecular clocks, either by personalized eating and exercise schedules or with the help of clock modulator molecules, we hope to ultimately be able to provide an innovative solution to an epidemical metabolic problem affecting an ever-increasing proportion of the world's population."

https://www.innovations-report.com/html/reports/medicine-health/could-resetting-our-internal-clocks-help-control-diabetes.html

Study links body clock to obesity and diabetes

From medicalxpress.com/news

                                                      Credit: CC0 Public Domain

Does skipping a meal at particular times of day reduce your chances of developing obesity or diabetes?

Are the street lights outside making you fat?

Research out of the University of Otago has found connections linking diabetes and obesity to circadian rhythm, often referred to as the body clock.
During the study the researchers examined the effects of disruption to the circadian rhythm of mice in a controlled laboratory setting. They found that repeated jetlag led to weight gain and severe diabetes symptoms.

We need to think about what disrupts our body clock. Anything that interferes with it, such as travel jetlag, social jetlag, shift work, bright-light exposure at the wrong time of day, can be detrimental for human health," says Associate Professor Alexander Tups of the University of Otago's Neuroendocrinology and Brain Health Research Centre.

"Very bright street lights disrupt melatonin, which is the hormone that regulates the circadian rhythm. This disruption can lead to obesity and diabetes if our studies can be translated to humans, but there is also accumulating evidence that disrupted melatonin secretion leads to cancer," Associate Professor Tups adds.

He hopes these findings will prompt experiments with humans to investigate which intensity of artificial light suppresses melatonin, and thereby would be detrimental for human health. This would lead to more informed decisions in choosing artificial light sources for their particular purpose.

A separate study also examined how the body clock influences the ability to process fatty food, and found supportive evidence for the popular diet technique of skipping a meal.
"Essentially, it matters what time you eat. Our bodies produce hormones which appear to work better at fighting off fatty foods consumed at particular times of day. If we avoid eating at times when these hormones are not working, we can reduce the detrimental effects of a fatty diet," Dr. Tups says.

The crucial hormone in regard to eating time is leptin; a body-weight regulatory hormone. Detrimental effects of high-fat feeding are exacerbated during leptin resistant times of the day.
The researchers discovered that contrary to current thinking, resistance against leptin is not universal throughout the day in obese mice.

"There are times when the mice were still sensitive to the hormone—so if the eating pattern is restricted to this time period the beneficial effects can be maximized," Dr. Tups says.
In mice it was particularly detrimental for metabolic health when access to fatty food was restricted to the late night and early morning, times when the animal was resistant to leptin. For mice, this would be dinner time, as they are active during the night and sleep during the day.

Because of this difference the Associate Professor Tups cannot yet give a clear recommendation which meal to skip to lose body weight.
"However, if the results were directly translatable to humans it would be most likely dinner. It needs to be in alignment with our body clock and would also depend on our individual chronotype, that means whether a person is a lark or an owl may make a difference about choosing which meal to skip," he adds.

Both studies are published in Endocrinology and the FASEB Journal.

https://medicalxpress.com/news/2019-08-links-body-clock-obesity-diabetes.html