People with type 2 diabetes are almost a third more likely to develop Parkinson’s disease in later life, a major study has found.
Research involving eight million people – including two million patients in England with type 2 diabetes – found the risk increased by 32 per cent.
Scientists from University College London found the risk was significantly higher for younger patients and those with complications from diabetes, such as eye and kidney damage.
The findings add to a growing body of evidence the diseases could be genetically linked or the result of insulin resistance on the brain.
Research involving more than two million patients in England with type 2 diabetes found the risk increased by 32 per cent
Professor Tom Warner, from the Neurology Institute at University College London, who led the study, said it was most comprehensive evidence to date to show a link.
‘There has been a suspicion that there may be a link between type 2 diabetes and Parkinson’s for some time,’ he said.
‘We can now say more definitely that there is a link between diabetes and Parkinson’s, but we need to do more research to understand the relationship – whether it’s due to genetics, the effect of diabetes on the brain, or both.
‘It’s significant in terms of what it is going to teach us about what’s going on in the brain in terms of how insulin and sugar are used and how we might be able to treat it better.’
What is Parkinson’s?
Parkinson’s is a degenerative neurological condition affecting a part of the brain that helps control movement, causing tremors and rigidity.
There are an estimated 145,000 people with the disease in the UK and there is currently no cure.
Rising numbers of people are being diagnosed with type 2 diabetes, fuelled by a rise in obesity and sedentary lifestyles.
How was the study carried out?
Researchers looked at data from the national hospital database over 12 years, identifying more than two million people who were admitted to the hospital for type 2 diabetes.
They were then compared to six million people without diabetes, admitted for a range of minor medical and surgical procedures like sprains, varicose veins, appendectomy and hip replacement.
Of the more than two million people with diabetes, 14,252 had a diagnosis of Parkinson’s disease during a later hospital admission.
What is type 2 diabetes?
- Type 2 diabetes is a condition which causes a person’s blood sugar to get too high.
- Over 4 million people in the UK are thought to have some form of diabetes.
- Type 2 diabetes is associated with being overweight and you may be more likely to get it if it’s in the family.
- Excess fat in the liver increases the risk of developing type 2 diabetes as the buildup makes it harder to control fasting glucose levels, and also makes the body more resistant to insulin. Weight loss is the key to reducing liver fat and getting symptoms under control.
- Symptoms include tiredness, feeling thirsty, and frequent urination.
- It can lead to more serious problems with nerves, vision and the heart.
- Treatment usually involves changing your diet and lifestyle, but more serious cases may require medication.
Source: NHS Choices; Diabetes.co.uk
This compared with 20,878 of the more than six million people without diabetes who were later diagnosed with Parkinson’s.
What did it find?
Once factors such as age, gender and background were factored in, they found that those with type 2 diabetes had a 31 per cent greater risk of a later diagnosis of Parkinson’s disease than those without diabetes.
The risk of being diagnosed with Parkinson’s disease later in life was four times higher for younger people, aged 25 to 44, suggesting the longer people had type 2 diabetes for, the greater the risk.
Those with complications from diabetes had a 49 per cent greater risk of a later diagnosis, they found.
Professor Warner said: ‘It looks like the worse the diabetes and the longer you have it, the higher your risk.’ Scientists believe the link could be due to a shared genetic predisposition to both conditions with previous studies finding more than 400 genes linked to both diabetes and Parkinson’s.’
Why does the link exist?
This could explain why the link was strongest among younger people, where genes may play a bigger role, the researchers added.
It may also be caused by the effect of diabetes on insulin signalling in the brain.
With type 2 diabetes, the body resists insulin which is necessary for converting glucose – or sugar – into energy.
As brain cells are particularly reliant on sugar for energy, it has long been speculated that the two diseases could be linked.
Dr Beckie Port, research manager at Parkinson’s UK, said it is the most robust evidence to date of a link.
‘The vast majority of people with diabetes will not go on to develop Parkinson’s.
‘Studies that demonstrate type 2 diabetes is linked to an increased risk of Parkinson’s suggest, however, that the two conditions may affect cells in similar ways.
‘Understanding the link between these two conditions could be key to developing treatments that slow the course of Parkinson’s, something that no current treatments can do.’