Type 2 Diabetes & Arthritis
Work in the garden one day, and you’re stiff the next. Take a long walk, and your knees ache. It’s just part of aging, right? Yes—but having type 2 diabetes may have something to do with it, too.
People with type 2 diabetes are almost twice as likely as people who don’t have it to develop osteoarthritis. Osteoarthritis is the most common form of arthritis and happens when the cartilage that cushions the ends of your bones wears down. A 2013 study from the University of Erlangen in Nuremberg, Germany, followed more than 900 people with and without type 2 diabetes for two decades. They found that people with diabetes are more likely to develop arthritis severe enough to need joint-replacement surgery.
Type 2 diabetes is more prevalent among people who are older and overweight, populations already at higher risk for arthritis. According to the U.S. Centers for Disease Control and Prevention (CDC), 50 percent of adults 65 and older have been diagnosed with arthritis, and according to the American Diabetes Association (ADA), almost 26 percent of adults 65 and older have type 2 diabetes. But that doesn’t fully explain why people with type 2 diabetes have achier knees and hips. When researchers accounted for both age and body mass index (BMI) in their data, the connection between blood glucose and joint health was still strong. The conclusion: Diabetes must have a direct effect on the joints. “Diabetes on its own is a predictor for severe osteoarthritis,” says the study’s author, George Schett, M.D.
Linking the Two
Scientists aren’t sure why diabetes contributes to joint damage, but they have theories. People with diabetes— especially those whose blood glucose levels stay too high over time—tend to have difficulty in healing, says George L. King, M.D., professor of medicine at Harvard Medical School. “That’s as true in the joints as other parts of the body,” he says. “It takes longer for joints to heal after injury—whether from exercise or normal use—and joint damage is the result.”
People with prediabetes and type 2 diabetes tend to be in a state of chronic inflammation, partly due to the result of insulin resistance. Insulin resistance, the body’s inability to efficiently use insulin the body continues to make, is a key issue in prediabetes and type 2 diabetes. A byproduct of this inflammation is the production of inflammatory substances, including some hormones that degrade joints. When researchers examined the knees of people with diabetes, they found more inflammation than in the joints of a similar group of people without diabetes, Schett says. He says controlling glucose may be essential to protecting joints from osteoarthritis.
Researchers are starting to think of osteoarthritis less as a wear-and-tear condition and more as part of the underlying changes in metabolism that occur with the development of prediabetes and type 2 diabetes—namely chronic inflammation, insulin resistance, and relatively insufficient amounts of insulin. These problems typically result in elevated blood pressure, high triglycerides, increased LDL (bad) cholesterol levels, low HDL (good) cholesterol levels, and a slow rise in blood glucose levels over time. When grouped together, some experts refer to this as metabolic syndrome.