How blood sugar stays steady overnight: Hidden network revealed

The brain plays a constant role in managing blood sugar, one of the body’s most vital energy sources. Every cell depends on glucose, and it’s the brain that helps prevent levels from rising too high or dropping too low.

For years, researchers have understood how the nervous system responds in emergencies like fasting or sudden dips in sugar, but its role in everyday control hasn’t been as clear.

That gap in knowledge has left big questions about how the body keeps itself stable from one day to the next. It also explains why even small disruptions in this system can set the stage for health problems over time.

Recent work shows that specific neurons in the brain take on the everyday task of keeping blood sugar steady under normal conditions. It’s another important clue to how the brain helps the body maintain its energy balance.

A master regulator in the brain

The hypothalamus, a small region deep in the brain, is already known as a master regulator. It controls hunger, temperature, fear responses, and even sexual behavior.

Within it lies the ventromedial nucleus, a hub that past studies linked to raising blood sugar during stressful events. What scientists wanted to know was whether this region also contributes during calm, routine conditions – like sleep.

The answer, it turns out, is yes. Researchers at the University of Michigan’s Caswell Diabetes Institute have pinpointed a set of neurons, called VMHCckbr neurons, that take on this task.

These cells contain a protein known as the cholecystokinin b receptor, and their role becomes especially important overnight.

Night shift for neurons

By studying mice, the team discovered that VMHCckbr neurons spring into action in the first few hours after bedtime.

Study co-author Dr. Alison Affinati described the important role of the neurons – which act as a safety net that operates while we sleep.

“In the first four hours after you go to bed, these neurons ensure that you have enough glucose so that you don’t become hypoglycemic overnight,” explained Dr. Affinati.

The process works through fat metabolism. The neurons signal the body to start lipolysis, breaking down stored fat into glycerol. That glycerol is then converted into sugar, helping keep glucose levels stable until morning.

Blood sugar control at night

To test how crucial these neurons are, the researchers turned them off in mouse models. When silenced, blood sugar control faltered during the early fasting hours of the night.

On the other hand, when the neurons were activated, glycerol levels rose, confirming their role in fueling overnight glucose production.

This activity may also shed light on prediabetes. People with prediabetes often show an increase in nighttime lipolysis. The study suggests that overactive VMHCckbr neurons could be part of the reason their blood sugar runs high.

More than a simple switch

“Our studies show that the control of glucose is not an on-or-off switch as previously thought,” said Dr. Affinati.

“Different populations of neurons work together, and everything gets turned on in an emergency. However, under routine conditions, it allows for subtle changes.”

This layered system ensures flexibility. One group of neurons may control fat breakdown, while others likely fine-tune sugar balance through different mechanisms involving the liver or pancreas.

That teamwork allows the body to adjust to different states – eating, fasting, or stress – without slipping into dangerous extremes.

The brain’s next puzzle

Scientists now aim to determine how all the various neurons in the ventromedial nucleus fit together. One part of that is mapping how brain signals feed into the liver and pancreas, which are key players in maintaining blood sugar levels.

Dissecting these connections could ultimately lead to new ways to attack metabolic disorders like diabetes, which afflicts millions of individuals.

What this research makes unmistakably clear is that blood sugar regulation is not all about crises – it’s something the brain is doing every day.

When we’re asleep, these neurons work quietly in the background, keeping balance so we have the fuel that we need in the morning.

The full study was published in the journal Molecular Metabolism.

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