A drug used to treat type 2 diabetes could significantly reduce the chances of getting dementia, research suggests.

Type 2 diabetics are known to have a heightened risk of going on to develop dementia, with the risk increasing the longer or more severe their diabetes is.

Researchers found that those who were taking sodium-glucose cotransporter-2 (SGLT-2) inhibitors to treat diabetes slashed the risk of dementia by up to half compared to those who did not.

Although preliminary findings, the results suggest repurposing existing drugs has ‘huge potential’ in helping to reduce risks of other disease.

Researchers analysed data from 110,885 type 2 diabetics aged between 40 and 69 on the Korea National Health Insurance Service.

They looked at patients were taking SGLT-2 inhibitors, which reduce the amount of glucose (sugar) - the kidneys reabsorb, allowing it to pass out of the body in urine.

These were then compared to those on dipeptidyl peptidase 4 (DPP-4) inhibitors, known as gliptins, which work by blocking an enzyme that helps the body increase insulin levels after eating.

During the average follow-up of about two years, 1,172 people were newly diagnosed with dementia.

Overall, dementia rates were 35 per cent lower for those taking SGLT-2 inhibitors when compared with the other medication.

This rose to 52 per cent for patients with vascular dementia and was 39 per cent for Alzheimer’s disease, according to the findings published in the BMJ.

The reduction in risk improved the longer a person took the drugs, researchers suggest, with scientists suggesting it could affect inflammation in the brain, reducing the risk for cerebrovascular events or modulating glucose metabolism in the brain.

Further ‘robust clinical trials’ are now needed to determine if this could be a feasible treatment in future, they said.

Dr Jacqui Hanley, head of research at Alzheimer's Research UK, said: ‘It is encouraging to see large studies exploring whether drugs that have already been licensed could be repurposed as dementia treatments.

‘Since these drugs have already been shown to be safe for use in people, this could potentially speed up the process of testing them in clinical trials against dementia, as well as making it significantly cheaper.’

She added: ‘More broadly, the idea of repurposing existing drugs to treat the diseases that cause dementia is one that has huge potential.’

It comes the week after regulators green-lit the first drug shown to slow down the progression of Alzheimer’s, but refused to authorise lecanemab for NHS use on cost grounds.

Professor William Whiteley, professor of neurology and epidemiology at the University of Edinburgh, warned the findings could be down to a ‘quirk of the study design’.

He said: ‘People with diabetes have a higher risk of dementia, so finding medicines to reduce this risk is important.

‘Unfortunately, one can never be sure about the effects of a medicine by looking at health record data.’