New research could explain why people with type 2 diabetes are more likely to develop dementia.
The findings may help identify risk factors for dementia in people with the condition and inform interventions to help prevent or delay the condition.
The research analysed cardiometabolic factors – such as blood pressure, blood sugars and cholesterol levels – in people with type 2 diabetes across two decades.
It identified changes in these factors during the study period that were associated with developing dementia in later life.
Dr Eszter Vamos, Diabetes UK-funded researcher at Imperial College London, said: “Our results emphasise the importance of carefully managing cardiometabolic factors such as blood pressure, cholesterol and glucose levels early on for people with type 2 diabetes.
“While this study cannot confirm causal associations, these results show that blood pressure and other cardiometabolic factors could be contributing to dementia development up to two decades before diagnosis.”
Dementia is more common in people with type 2 diabetes, but why people with the condition are more at risk has not been clear.
High blood sugar levels, blood pressure and cholesterol in people with type 2 diabetes can damage blood vessels and lead to serious cardiovascular problems, such as heart attacks and strokes.
In the past it has been suggested these factors might also affect brain health and could potentially play a role in the development of dementia in people with type 2 diabetes.
Researchers looked to see if the factors affecting heart health in people with type 2 diabetes could also impact their dementia risk.
They analysed data from 227,580 people with type 2 diabetes over the age of 42 years, around 10% of whom went on to develop dementia.
The team examined the participants’ medical history across the 20 years prior to their dementia diagnosis to look at changes in cardiometabolic factors and body weight, and compared these with people who did not develop dementia.
Over the 20 years, changes in blood pressure differed between those who did and did not develop dementia.
People who developed dementia had higher blood pressure between 11-19 years before their dementia diagnosis, which then declined more steeply closer to their diagnosis, compared with those who did not develop dementia, researchers say.
According to the research presented at the Diabetes UK Professional Conference (DUKPC) 2021, decline in body weight starting at 11 years before a dementia diagnosis was found in people who developed the condition and this was steeper than in those who did not.
Blood sugar and cholesterol levels were also found to be generally higher across the entire 20-year period among people with type 2 diabetes who developed dementia, compared with those who did not.
Eating healthily, keeping active, reducing alcohol intake and stopping smoking are all advised to help everyone reduce their risk of dementia.
Researchers say the findings suggest that by monitoring cardiometabolic factors and managing blood sugar, blood pressure, cholesterol and body weight, people with type 2 diabetes could be supported to lower their risk of dementia.
Dr Elizabeth Robertson, director of research at Diabetes UK, which funded the study, said: “These crucial findings have uncovered how type 2 diabetes may contribute to dementia onset.
“Changes in the body that lead to dementia occur years before symptoms arise, and for the first time, researchers have uncovered a pattern of changes in people with type 2 diabetes that are associated with dementia.
“Knowing which factors contribute to the development of dementia, and when they have the biggest impact, is vital in giving people with type 2 diabetes the best possible care to prevent or delay dementia onset.”