Research from UNSW Sydney suggests that older people with type 2 diabetes who take the drug may experience slower memory and thinking decline.
Type 2 diabetes develops when the body cannot use insulin effectively or does not produce enough of it. Insulin helps move sugar from the bloodstream into cells, where it can be used for energy.
When this process stops working properly, blood sugar can remain too high for long periods. Over time, this can damage blood vessels, nerves, kidneys, eyes and the heart, and diabetes has also been linked with a greater risk of problems affecting the brain.
People with type 2 diabetes have a higher risk of developing dementia than people without the condition. Dementia is a broad term for illnesses that cause worsening memory, thinking and the ability to manage everyday life.
Metformin has been prescribed for type 2 diabetes for decades. It mainly helps by reducing the amount of sugar released by the liver and improving the body’s response to insulin.
Researchers led by Professor Katherine Samaras at UNSW Sydney wanted to know whether metformin might also be linked with better brain health. They studied older adults over time and compared changes in memory and thinking between people who used metformin and those who did not.
The analysis included 123 participants with type 2 diabetes. Among them, 67 were taking metformin as part of their diabetes treatment.
During follow-up, the researchers found that participants taking metformin had less decline in their thinking abilities than those who were not taking the drug. They also appeared to have a lower risk of developing dementia.
The finding is important because there is growing interest in the connection between diabetes and brain aging. High blood sugar, insulin resistance, inflammation and damage to blood vessels may all contribute to changes in the brain over many years.
Metformin could potentially influence some of these processes. Scientists have suggested that its effects on blood sugar, insulin sensitivity and other biological pathways might help explain the possible connection with healthier brain aging.
However, the study does not prove that metformin itself prevented dementia. It was an observational study, meaning researchers examined what happened to people already receiving different treatments rather than randomly assigning them to take metformin or another treatment.
People who take metformin may differ from those who do not in ways that could also influence dementia risk. The relatively small number of participants means larger studies are needed before scientists can be confident about the size of any protective effect.
Metformin has attracted scientific attention for possible effects beyond diabetes. Researchers have investigated its relationship with cardiovascular health, cancer, aging and weight, and the medicine is also commonly used for conditions such as polycystic ovary syndrome.
The possibility that it could influence brain health is particularly interesting because dementia becomes more common with age. Finding safe and affordable ways to delay memory decline could have a major impact as populations around the world grow older.
For now, people without diabetes should not take metformin in an attempt to prevent dementia. The medicine can cause side effects and is not suitable for everyone, and researchers still need clinical trials to determine whether it can directly protect memory or prevent dementia.
The UNSW Sydney research was published in the journal Diabetes Care. The findings suggest that an established and inexpensive diabetes medicine may deserve further investigation as scientists search for new ways to protect the aging brain.
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