- A large UK Biobank analysis found higher blood glucose was linked with older-looking brains on MRI scans.
- Glucose showed the strongest association among nine blood metabolites linked to brain age.
- The findings suggest blood sugar control may matter for brain health, not just diabetes and heart disease.
Blood sugar is usually discussed in relation to diabetes, weight and heart health.
A new study suggests it may also be tied to how quickly the brain ages.
Researchers analysed MRI scans, blood metabolite data and genetic information from the UK Biobank.
They used artificial intelligence to build a “brain age” model from more than 1,000 imaging-derived brain features.
The model estimated how old a person’s brain appeared compared with their actual age.
This difference is called the brain age gap.
A higher brain age gap suggests the brain looks older than expected.
The researchers then looked at blood metabolites linked to this gap.
Nine stood out.
Glucose had the strongest association.
People with higher blood glucose tended to have brains that looked older on scans.
The researchers also found genetic evidence supporting a possible causal role for glucose in accelerated brain ageing.
Higher glucose was linked with smaller volumes across 80 brain regions, including cortical, subcortical and cerebellar areas.
It was also associated with higher risk of several brain-related conditions.
These included all-cause dementia, Alzheimer’s disease, vascular dementia, Parkinson’s disease, stroke, depression and anxiety.
Cognitive performance, movement function and mental health outcomes were also poorer where glucose levels were higher.
This does not mean a single blood sugar reading tells you your brain age.
- Metformin may lower blood sugar mainly through the gut
- Metformin may lower blood sugar through the brain as well as the body
- Getting blood sugar back to normal may cut heart risk in prediabetes
Nor does it mean glucose is the only thing that matters.
Brain ageing is shaped by many factors, including blood pressure, sleep, physical activity, smoking, inflammation and education.
But the study adds weight to a bigger idea.
Metabolic health and brain health are not separate systems.
Keeping blood glucose in a healthy range may be one of the ways to protect the brain across the lifespan.
That matters for people with diabetes, but also for anyone drifting into poor metabolic health long before diagnosis.
