There’s research that suggests a connection between rheumatoid arthritis (RA) and diabetes. But the nature of that connection or even whether it’s actually real is unclear. "There are tantalizing links between the two diseases,” says Daniel Solomon, MD, MPH, an associate professor of medicine at Harvard Medical School and a rheumatologist at Brigham and Women's Hospital in Boston. But "at this point they are mainly speculative."
WebMD asked Solomon and Androniki Bili, MD, MPH, to explore the possible connection between RA and diabetes. Bili is an associate rheumatologist at Geisinger Health System in Danville, Pa. Here is what they had to say and how it might affect the way you manage RA.
RA/Diabetes Connection: What Are the links?
There are a number of theories about the connection between diabetes and rheumatoid arthritis. RA is an autoimmune disease. The immune system defends the body from invading organisms and substances that can cause damage. With RA, the body’s immune system attacks its own joints. The result of that attack is an ongoing inflammation, which is a hallmark of RA. Some research suggests that inflammation may also play a role in the onset of diabetes.
Solomon tells WebMD that there are links between inflammation and insulin resistance. "We know there is an increased risk of insulin resistance among people with RA," he says. Insulin is produced in the pancreas and helps the body use glucose, or blood sugar, for energy. In people with insulin resistance, the body’s cells don’t respond to insulin in the correct way. That increases the risk of developing type 2 diabetes.
But inflammation is not the only potential link between RA and diabetes. Certain drugs that are used to treat RA, namely steroids, may actually increase the risk of diabetes. "We need to be very aware of RA patients' glucose levels, especially if they are on corticosteroids,” says Solomon. “This drug is a risk factor for hyperglycemia or high blood sugar levels."
The effects of RA may also increase the risk of diabetes. People with RA may lead sedentary lives due to pain and RA-related disabilities. When people are physically inactive, they are more likely to be overweight. Being overweight or obese is a known risk factor for diabetes. And according to the CDC, the inactivity caused by arthritis interferes with management of both RA and diabetes.
RA/Diabetes Connection: Can the Risk Be Lowered?
”If a patient has any modifiable risk factors for diabetes such as obesity,” Solomon says, “I want to be as proactive as possible." This means encouraging the patient to eat a healthful diet and get regular exercise. Doing so will help lose weight and reduce the risk of diabetes.
And treating RA may also play a role in reducing the risk of diabetes. While steroids can increase diabetes risk, other rheumatoid arthritis medications may actually help lower the risk. For example, studies show that the antimalarial drug hydroxychloroquine is associated with a decreased risk of diabetes among people with RA.
In one study, people with RA who had ever taken hydroxychloroquine were 53% less likely to develop diabetes than their counterparts who had never taken it. In another study of patients with RA, researchers found that having ever taken hydroxychloroquine reduced the risk of diabetes by 38%. What’s more, people with RA who took hydroxychloroquine for more than four years were 77% less likely to report a new diabetes diagnosis than those who never took it.
“This is a safe and inexpensive drug and it has been consistently shown to decrease the risk of diabetes in RA,” says Bili, the author of the first study.
RA/Diabetes Connection: Making Informed Choices to Reduce the Risk
Does the effectiveness of hydroxychloroquine in reducing diabetes risk mean all people with RA and risk factors for diabetes should take it?
“It is a reasonable choice,” Bili says, “but it is a weaker treatment for RA. It may not achieve disease control.” Other drugs are more effective when it comes to treating the pain and inflammation of RA. “But, says Bili, “for people with mild RA who have risk factors for diabetes, it might be reasonable to start treatment with hydroxychloroquine. If they have more severe RA, she tells WebMD, hydroxychloroquine could be taken in combination with another arthritis drug.
It’s not clear why hydroxychloroquine is associated with lower diabetes risk among people with RA. It may allow the hormone insulin to remain in the body longer. This could improve insulin sensitivity and glucose tolerance and prevent diabetes.
Solomon says that what is known now is that insulin resistance is elevated in RA, but certain RA drugs such as TNF blockers, hydroxychloroquine, and methotrexate may improve insulin sensitivity. "Studies show that TNF antagonists taken for a month or a year improve insulin resistance,” Solomon says. "But we don't know if this will lead to reduced diabetes risk."
Many important questions remain about the link between diabetes and arthritis. "We don't know whether tighter control of RA will reduce the risk of diabetes," Solomon says. A study that looks at the effect of better RA control in reducing the risk of diabetes would, he says, “be a wonderful trial."
In the meantime, it’s important to keep in mind that making healthy lifestyle choices involving exercise, diet, and not smoking is an important part of RA management. And those same choices are important in managing the risk of diabetes.