We usually think of blood sugar as something determined by what we eat, how much we exercise, our metabolism and our genes.

But a new study suggests another factor may belong on that list: who is sitting next to you.

Researchers found that people’s bodies regulated blood sugar more efficiently when their romantic partner was present than when they were alone. After consuming the same amount of carbohydrate, participants experienced a smaller disruption in blood glucose and returned toward baseline faster when their partner was nearby.

The difference was not trivial. The researchers reported an approximately 15 percent reduction in the overall glucose response in the social condition.

The finding raises an intriguing possibility: some of the health benefits associated with close social relationships may operate through surprisingly basic physiological processes.

The same food raised blood sugar less in a partner’s company

The study, published in Science Advances in September 2026, involved 108 adults in its glucose experiment.

Participants consumed a standardized carbohydrate challenge under two conditions: alone and in the presence of their romantic partner. Because the food was controlled, the researchers could examine whether social presence itself changed the body’s response.

It did.

With their partner present, participants showed a smaller rise in glucose and faster recovery toward their starting level. The researchers describe this as more efficient glucose homeostasis, the body’s ability to keep blood sugar within a stable range despite disturbances such as eating.

And glucose was not the only system affected.

Separate experiments found more efficient thermoregulation during exposure to cold and reduced sympathetic nervous-system responses during stress when another close person was present. The stress effect was also tested in infants with their mothers.

The researchers call the broader phenomenon “Social Physiology.” Their proposal is that human homeostasis may not be entirely an individual process. Our bodies may regulate themselves differently depending on the social environment around us.

Repeated high spikes after meals are linked to heart risk

A rise in blood glucose after eating carbohydrates is normal. The interesting question is what happens if glucose rises unusually high or remains elevated repeatedly over long periods.

Here, earlier research provides an important clue.

In a study following more than 15 000 people without diabetes or cardiovascular disease, higher glucose levels two hours after a meal predicted a greater risk of cardiovascular death even after researchers accounted for factors including age, smoking, blood pressure and cholesterol.

Other research has similarly linked exaggerated post-meal glucose responses with cardiovascular risk. Possible mechanisms include oxidative stress, inflammation and impaired function of the endothelium, the layer of cells lining blood vessels.

That makes the new finding potentially important.

If being around someone close to us repeatedly changes the way our bodies handle glucose, the effect could conceivably accumulate over years.

But that remains a hypothesis.

What the study does not tell us

The new research does not show that eating with your partner prevents diabetes, protects against heart disease or extends your life.

Nor can we take the roughly 15 percent difference in glucose response and translate it into a corresponding reduction in disease risk.

There is an important distinction between the two bodies of evidence. The new study shows that social proximity can alter short-term glucose regulation. Earlier observational research shows that elevated post-meal glucose is associated with poorer long-term cardiovascular outcomes.

No study has yet demonstrated the entire chain:

eating with someone close → consistently lower glucose responses → lower risk of disease years later.

Even the role of post-meal glucose itself requires some caution. Although elevated postprandial glucose predicts cardiovascular risk, clinical trials attempting to reduce cardiovascular disease specifically by targeting glucose excursions have produced less definitive evidence about causation.

That is an important unanswered question rather than a reason to dismiss the finding.

Social relationships may reach into basic physiology

Scientists have long known that social relationships are associated with health. Social support can influence stress, behavior and psychological well-being.

What makes this study unusual is the suggestion that the effect may reach into physiological systems that we would not normally consider social at all.

Blood glucose regulation seems like an internal metabolic process. Yet the same carbohydrate challenge produced a measurably different response depending on whether someone close was present.

If future studies find that these small physiological differences persist in everyday life and accumulate over months or years, they could provide one piece of the explanation for why our relationships and our health are so closely connected.

For now, the evidence supports a more modest but perhaps equally remarkable conclusion:

Your body may not regulate itself entirely on its own.