The research, published this week in the Canadian Medical Association Journal by scientists from China, Taiwan, and Australia, showed an association between regular use of metformin and about a 30 percent reduced likelihood of needing total knee replacement or total hip replacement. This association did not mean that metformin was conclusively proven to cause a lower rate of joint replacements, according to study authors. Joint replacements are a common treatment for people with advanced osteoarthritis, a chronic joint disorder that often leaves older people in pain and unable to walk or perform other daily functions. Diabetes has been linked with a greater risk of osteoarthritis. In the United States, the number of total knee replacement and total hip replacement surgeries is projected to reach 572,000 per year by 2030. No medications are currently known to prevent or reverse osteoarthritis. “The current study suggests consistent benefits of metformin use for osteoarthritis management among patients with type 2 diabetes mellitus,” says lead study author Zhaohua Zhu, PhD, an associate professor at Zhujiang Hospital of Southern Medical University in China. “The findings may stimulate future clinical trials to test the efficacy and effectiveness of metformin for osteoarthritis treatment.”
Prior Studies Have Suggested Metformin May Protect Against Osteoarthritis in People With Diabetes
Dr. Zhu and colleagues analyzed data from the Taiwan National Health Insurance Research Database from patients with type 2 diabetes who were diagnosed between 2000 and 2012. The average age of those studied was 63, with participants almost evenly split between men and women; the patients were followed for about 14 years. The study team observed that about 90 percent of total joint replacements were related to osteoarthritis. The new investigation backs up prior studies showing that metformin may provide protection against osteoarthritis. A report published in July 2022 in Scientific Reportssuggested a potential shielding effect of metformin on the worsening of knee osteoarthritis. Another study, published in September 2022 in Cells, revealed that metformin may delay the development and progression of osteoarthritis.
Why Might Metformin Be Good for the Joints?
Marilyn Tan, MD, an endocrinologist at Stanford University in California who was not involved in the study, said that metformin may guard against osteoarthritis by reducing overall inflammation. “Improved glucose control can improve overall infection risk and inflammation, and it’s possible that some of the decreased inflammation contributed to lower rates of knee replacement and hip replacement,” says Dr. Tan. She adds: “Metformin is also generally thought of as a weight-neutral medication, but sometimes patients can lose weight on it, which could also help reduce the need for hip or knee replacement.”
Metformin Not Yet Recommended for Osteoarthritis Without Diabetes
According to Zhu, future trials should examine the effect of metformin on osteoarthritis, particularly in overweight osteoarthritis patients. Tan warns that she would not go as far as recommending metformin at this time for people who have osteoarthritis but don’t have diabetes. “Further studies are needed to elucidate the exact mechanism of the association between metformin and joint replacement risk,” Tan says. “Metformin is not FDA-approved for use in patients without diabetes, but it would be interesting to see the effects of metformin on osteoarthritis in patients who do not have diabetes.”
