Metformin is one of the most commonly used diabetes treatments, with more than 120 million people being prescribed the medicine worldwide. It works by making the cells more receptive to insulin and decreasing the amount of glucose released into the bloodstream by the liver.
People with diabetes are more likely to have mood disorders such as anxiety and depression, and insulin resistance (a key characteristic of type 2 diabetes) has been linked to depression in previous research. In the current study, investigators found that, in mice raised on a high-fat diet, metformin reduce anxiety-like behaviors by increasing the availability of serotonin (also known as the “happiness hormone,” a chemical messenger thought to be involved in regulating mood) in the brain. According to the Society for Neuroscience, “These findings could have implications for the treatment of patients with both metabolic and mental disorders.”