Common diabetes drug may help manage knee arthritis, obesity

Researchers from Monash University in Australia showed that metformin -- commonly prescribed to treat type 2 diabetes -- can reduce knee arthritis pain in people without diabetes.

"Metformin is a potentially new and affordable way to improve knee pain in those with knee OA and overweight or obesity," said lead researcher Professor Flavia Cicuttini, who heads Musculoskeletal Unit at the varsity.

The six months-long randomised clinical trial, performed entirely as a community-based study using telehealth, involved 107 participants with pain from knee osteoarthritis (73 women and 34 men), with a mean age of 60. The participants took up to 2,000 mg of metformin daily for six months. Others took the placebo. None had diabetes.

Knee pain was measured on a 0-100 scale, with 100 being the worst.

In the results, published in JAMA, the metformin group reported a 31.3 point reduction in pain after six months, compared to 18.9 for the placebo group. This was considered a moderate effect on pain.

Knee OA treatments include lifestyle approaches such as exercise and weight loss, which patients often find difficult, and medications such as paracetamol, topical anti-inflammatory creams, and oral anti-inflammatory medications which have small benefits and may be unsuitable for some patients for safety reasons.

Professor Cicuttini said effective treatments that improved knee pain in osteoarthritis were limited. She said this led some patients and their doctors to seek alternative treatments including surgery.

This resulted in major problems managing knee OA, including an increase in the rate of knee replacements performed for earlier stages of OA.

Professor Cicuttini said metformin now provided GPs an alternative they could offer patients in addition to managing weight and increasing activity.

"Metformin works in a number of ways on the knee, including affecting low-grade inflammation and other metabolic pathways that are important in knee OA," she said.

Stating that Metformin is "low-cost and safe medication," the expert noted it "has the potential to delay people having knee replacements before they are absolutely needed. If people on metformin have less knee pain and are able to do more physical activity, then knee replacements can wait."

However, the researchers also called for a larger clinical trial as the study had a small sample size.