Having prediabetes could impact someone’s brain health, researchers have found.

People with prediabetes means they have higher than normal blood sugar levels, but they are not high enough to qualify for a type 2 diabetes diagnosis.

A team from University College London (UCL) say they have found a link between the condition and cognitive decline.

A trial involving 500,000 people aged around 58 found there was a 42% higher chance of people suffering from frequent confusion or memory loss over a four-year period.

However, over an eight-year time period the risk of developing vascular dementia increased to 54%.

Lead author Dr Victoria Garfield, from UCL’s Institute of Cardiovascular Science and the UCL MRC Unit for Lifelong Health & Ageing, said: “Our research shows a possible link between higher blood sugar levels, a state often described as ‘prediabetes’, and higher risks of cognitive decline and vascular dementia.

“As an observational study, it cannot prove higher blood sugar levels cause worsening brain health. However, we believe there is a potential connection that needs to be investigated further.

“Previous research has found a link between poorer cognitive outcomes and diabetes but our study is the first to investigate how having blood sugar levels that are relatively high, but do not yet constitute diabetes, may affect our brain health.”

The trial involved testing how different blood sugar levels related to brain health and cognitive tests over time. They used MRI brain scans to measure any changes.

Senior author Professor Nishi Chaturvedi, from UCL’s MRC Unit for Lifelong Health & Ageing, added: “In this relatively young age group, the risks of cognitive decline and of dementia are very low; the excess risks we observe in relation to elevated blood sugar only modestly increase the absolute rates of ill health. Seeing whether these effects persist as people get older, and where absolute rates of disease get higher, will be important.

“Our findings also need to be replicated using other datasets. If they are confirmed, they open up questions about the potential benefits of screening for diabetes in the general population and whether we should be intervening earlier.”

The findings have been published in the Diabetes, Obesity and Metabolism journal.

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