PATIENTS with Type 2 diabetes undergoing metformin therapy could be at a lower risk of osteoarthritis that those undergoing sulfonylurea treatment, according to data from a team at the Division of Immunology and Rheumatology at Stanford University, California, USA. Building on previous research in animal models, Matthew Baker, Stanford University, commented that the study was designed to “see if there was an epidemiological signal for benefit of treatment with metformin in humans.”
The retrospective cohort study analysed the data of patients who were aged 40 years or older, had at least 1 year of enrolment in the database before being diagnosed with diabetes, and received either metformin or sulfonylurea treatment. Included patients were then split into two groups for analysis. The test group received metformin, while the control group received sulfonylurea for at least 90 days. The measured outcome was the time to diagnosis of osteoarthritis from 90 days following the initiation of treatment. The diagnosis of osteoarthritis, ceasing treatment, undergoing joint replacement procedures, and beginning therapy with a different diabetes drug were additional outcomes that were recorded.
Each group included 20,937 patients, with results indicating that metformin treatment decreased the risk of osteoarthritis by 24% when compared to sulfonylurea treatment (adjusted hazard ratio [aHR]: 0.76; 95% confidence interval [CI]: 0.68–0.85). However, no significant difference was reported in the incidence of joint replacement between the two groups (aHR: 0.8; 95% CI: 0.5–1.27). The decreased risk of osteoarthritis in the metformin group (aHR: 0.77; 95% CI: 0.65–0.90) and non-significant difference in incidence of joint replacement (aHR: 1.04; 95% CI: 0.60–1.82) remained in the sensitivity analysis.
Overall, Baker commented: “We found that patients treated with metformin had a lower incidence of OA compared with controls.” Baker went on: “This is not enough data to suggest using metformin in the clinic yet for OA, but it does lay the foundation for a future, prospective, interventional trial to determine if metformin might be an effective therapeutic for OA.” Baker added that metformin has the potential to prevent, slow or stop the progression of the disease and therefore, “We are excited about future work in this space.”