Metformin, one of the most commonly advised diabetes drugs, may have an unexpected, but positive, effect on the body.

A new study has suggested that diabetics who are taking metformin appear to have a delayed decline in thinking and memory as age progresses.

Study author Dr. Katherine Samaras of the Garvan Institute of Medical Research in New South Wales said, “Our six-year study of older Australians with type 2 diabetes has uncovered a link between metformin use and slower cognitive [mental] decline and lower dementia rates.”

“The findings provide new hope for a means of reducing the risk of dementia in individuals with type 2 diabetes, and potentially those without diabetes,” she added.

Sold under the brand name Glucophage and others, metformin helps the body to use the hormone insulin more effectively, working as an insulin sensitizer.

Insulin regulates blood sugar levels by taking the sugar into the body’s cells for energy purposes. Type 2 diabetics do not use insulin effectively, which is called insulin resistance.

Dr. Samaras explained, “Metformin is an insulin-sensitizing medication. However, it has a number of other effects in cells which allow them to remain metabolically healthy.”

The study, published online Wednesday in Diabetes Care, examined more than 1,000 people, aged between 70 and 90, for six years. All of the participants had no signs of dementia. They had to undergo a series of neuropsychological tests every two years. More than 120 had diabetes and 67 were taking metformin.

The researchers found that diabetics who did not take metformin had a greater risk of developing dementia during the study period.

Previous studies have also found that metformin could help lower dementia risk. The current study aimed to understand whether the drug made a difference in slowing down declines in memory and thinking.

“Our study has provided promising initial evidence that metformin may protect against cognitive decline,” said Dr. Samaras. “[The new] trial will reveal whether metformin can assist in preventing against cognitive decline in older people more broadly.” She noted that metformin is an inexpensive drug and has few side effects – such as digestive problems, typically occur during the first few weeks of the treatment.