The drug metformin is linked to slower cognitive decline and lower dementia rates in people with type 2 diabetes, according to a six-year study in older adults.

The researchers examined data from participants in the Sydney Memory and Aging Study. Fully 123 had type 2 diabetes, and 67 used metformin to regulate blood sugar levels. Cognitive function was tested every two years, using detailed assessments that measured factors including memory, executive function, attention and speed, and language.

Participants who took metformin were less likely to develop dementia, and cognitive decline progressed more slowly in this group when compared with participants who did not take metformin. In addition, there was no difference in the six-year rate of cognitive decline between the metformin users and their peers without diabetes.

The findings provide new hope for reducing the “staggering” 60% dementia risk in individuals with type 2 diabetes — and potentially even in those without diabetes, said Katherine Samaras, Ph.D., an endocrinologist and researcher with the Garvan Institute of Medical Research, Sydney, Australia.

“We’ve revealed promising new potential for a safe and widely used medication — which could be life-changing for patients at risk of dementia and their families,” Samaras said. “For those with type 2 diabetes, metformin may add something extra to standard glucose lowering in diabetes care: a benefit for cognitive health,” she concluded.

Samaras’s team last year published a study finding that statins are not linked to cognitive decline in the elderly.

The current study was published in Diabetes Care.