Researchers call for trial of metformin as potential treatment for osteoarthritis

A medication for patients with type 2 diabetes significantly reduces the risk of joint replacements, researchers have found.

A commonly prescribed medication for patients with type 2 diabetes significantly reduces the risk of joint replacements, Australian and international researchers have found.

Metformin was associated with a 30 per cent reduction in risk of joint replacements in patients with type 2 diabetes who were taking the drug, according to the large study published in the Canadian Medical Association Journal today.

The results have prompted the authors to call for randomised controlled trials to determine whether metformin could be effective in treating patients with osteoarthritis (OA).
They said metformin had been studied in patients without diabetes mellitus and “was found to be safe.”

“We found that metformin use in patients with type 2 diabetes mellitus was associated with a significantly reduced risk of joint replacement, suggesting a potential therapeutic effect of metformin in patients with OA,”

“Randomised controlled clinical trials are warranted to determine whether metformin is effective in patients with OA.”

A normal knee (left image) and osteoarthritis knee (right image).

Australian researchers from the University of Sydney Menzies Institute for Medical Research, as well as colleagues from China and Taiwan analysed data from almost 70,000 patients who received a diagnosis of type 2 diabetes in Taiwan between 2000 and 2012.

They compared the risk of total knee replacement (TKR) and/or total hip replacement (THR), between people taking metformin and those not taking metformin.

The mean age was 63 years and half were women. About 90 per cent of total joint replacements were related to osteoarthritis.

Osteoarthritis is a common chronic condition that usually causes joint pain and can be severe enough to require knee and hip replacements.

No medications are currently known to prevent or reverse osteoarthritis.

Other studies have evaluated the association between metformin use and OA in patients with diabetes, the researchers reported.

Most recently, a large retrospective study conducted among 93,330 patients with type 2 diabetes mellitus found that regular metformin users had a 19 per cent lower risk of TKR than non-users over their four-year follow-up period, consistent with their findings.

Even the prospect of a potential treatment for OA is likely to be welcomed by millions of Australians.

Osteoarthritis affects about a third of Australians aged over 75 years.

According to the Australian Institute of Health and Welfare OA is the most common form of arthritis in Australia. Australian Bureau of Statistics data from 2017-2018 estimated that 2.2 million Australians have the condition.

Although OA affects people of all ages, the prevalence increases sharply from the age of 45 years. One in five Australians (22 per cent) over the age of 45 have OA, and it is most common in adults aged 75 years and over, affecting over one-third (36 per cent) of people in this age group.

The condition is more common among females than males, affecting 10 per cent of females compared with 6.1 per cent of males (after adjusting for age).

OA is caused by the breakdown of the cartilage that overlies the ends of bones in joints. This results in the bones rubbing together, causing pain, swelling and loss of motion. It mostly affects the hands, spine and joints such as hips, knees and ankles, and usually gets worse over time.

Genetic factors, excess weight, joint misalignment, joint injury or trauma (such as dislocation or fracture), and repetitive joint-loading tasks (for example, kneeling, squatting and heavy lifting) can all contribute to OA onset and progression.

Canadian Medical Association Journal 2022, online December 19