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Osteoarthritis risk lower in type 2 diabetics taking metformin

The risk of developing osteoarthritis is lower in type 2 diabetic patients taking metformin than among those taking sulfonylureas

Osteoarthritis (OA) is a common form of arthritis which globally affects 528 million people. Treatment focuses on drug therapy, self-management and exercise. In addition, there are currently no preventative therapies available. Metformin is an oral hypoglycaemic agent for the treatment of type 2 diabetes. The drug also appears to have other actions including the ability to suppress inflammation. In fact, there appears to be a beneficial effect on long-term knee joint outcomes in those with osteoarthritis and obesity. However, whether metformin can prevent the development OA is less clear.

In the current study, US researchers explored if metformin was able to lower the risk of developing OA as well as the need for joint replacement in type 2 diabetics. The team undertook a retrospective analysis using sulfonylureas as a comparator anti-diabetic therapy. Individuals with a prior diagnosis of OA were not included in their analysis. Researchers propensity-matched metformin and sulfonylurea patients 1:1. The primary outcome of interest was the time to an incident diagnosis of OA, 90 days after starting either medication.

Osteoarthritis development and anti-diabetic therapy

There were 41,874 individuals with a mean age of 62 years (41.8% female) with usable data for analysis. Among this total, 20,937 were receiving metformin.

The risk of developing osteoarthritis was 24% lower in those using metformin than a sulfonylurea (Hazard ratio, HR = 0.76, 95% CI 0.68 – 0.85, p < 0.001). However, there was no significant difference between the two groups in the risk for joint replacement (HR = 0.80, 95% CI 0.50 – 1.27, p = 0.34). Similar findings were obtained in a sensitivity analysis (HR = 0.77, 95% CI 0.65 – 0.90, p < 0.001) for OA.

These findings led the authors to suggest that metformin may have a protective effect against the development of OA.