Study: Drug against type 2 diabetes reduces dementia risk by 35% | Dementia

A drug used to treat type 2 diabetes is associated with a 35 percent lower risk of dementia, according to a study.

By 2050, the number of people with dementia worldwide is expected to triple to 153 million. Research suggests that the health and social costs associated with dementia already exceed $1 trillion (£780 billion) a year.

Type 2 diabetes is one of 14 risk factors associated with a higher risk of developing dementia. Other factors include high cholesterol, untreated vision loss, hearing impairment, high blood pressure, smoking, obesity and lack of exercise.

A large Korean study published in the BMJ now suggests that a drug used to treat type 2 diabetes called sodium-glucose cotransporter-2 (SGLT-2) inhibitors may reduce the risk of dementia.

While previous studies suggested that SGLT-2 inhibitors may have a protective effect against dementia in older patients, it was previously unclear whether there was a protective effect on younger people and certain types of dementia such as Alzheimer's disease and vascular dementia.

The scientists analyzed data from more than 220,000 type 2 diabetics aged between 40 and 69 who were enrolled in the Korean National Health Insurance and did not already suffer from dementia.

Half of the patients took SGLT-2 inhibitors, which reduce the amount of glucose reabsorbed by the kidneys, and the other half took another drug called dipeptidyl peptidase-4 inhibitors (DPP-4 inhibitors), which blocks the enzyme that causes insulin levels to rise after eating.

During the study period, a total of 1,172 participants were identified who were newly diagnosed with dementia.

The researchers calculated that SGLT-2 inhibitors were associated with a 35 percent lower risk of dementia compared to DPP-4 inhibitors. They also found that patients taking SGLT-2 inhibitors had a 39 percent lower risk of Alzheimer's disease and a 52 percent lower risk of vascular dementia.

The authors pointed out that this was an observational study and therefore could not prove cause and effect. However, they concluded that repurposing existing drugs to treat dementia has “huge potential.” However, further studies are needed to confirm their findings.

Dr Jacqui Hanley, head of research at Alzheimer's Research UK, said the data was “promising”, adding: “People suffering from dementia urgently need effective treatments, as the news of Nice's rejection of the Alzheimer's drug lecanemab last week underlined.”

Repurposing drugs that are already approved to treat dementia could speed up the clinical trial process and make it significantly more cost-effective, she said. “If we want to cure dementia, doctors need a treatment package that addresses different aspects of the disease and can be used in combination. Research into drug repurposing could help us do that.”

But Prof William Whiteley, deputy director of the British Heart Foundation's data science centre, said: “If this study is correct, SGLT-2 inhibitors would almost halve the risk of some forms of dementia, and that is a much greater effect than that of drugs to slow the progression of dementia or prevent heart attacks and strokes.”

“Instead, a peculiarity of the study design probably led to this result.”