Traditionally, type 1 diabetes and rheumatoid arthritis have been grouped together as autoimmune diseases — conditions in which your body’s immune system mistakenly attacks healthy tissue. There’s a lot we don’t understand about why an autoimmune attack happens, but there are ways to analyze and measure what’s going on — such as by testing for autoantibodies, proteins that your immune system creates as part of an attack against a specific type of cell or tissue in your body.
In rheumatoid arthritis, there are also many chemicals that your body creates when disease activity is high, as part of an inflammatory process involving joints affected by the disease. There has long been speculation that inflammation may play a role in the development of diabetes — especially type 2 — and over the years, some evidence has been found to support this idea.
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Now, a new study is putting inflammation back in the spotlight as a possible contributor to diabetes — finding that disease activity in people with rheumatoid arthritis is tied to the risk of developing diabetes.
Disease activity and inflammatory markers tied to diabetes
The new study, published in the journal Annals of the Rheumatic Diseases, looked at 1,866 people with a confirmed diagnosis of rheumatoid arthritis — but without diabetes — who took part in the Veteran’s Affairs Rheumatoid Arthritis Registry. As part of their care in the VA system, participants received periodic disease assessments, with clinical assessments and periods of disease activity noted in their records. At the beginning of the study, participants gave blood samples that were tested for the levels of 30 different substances known as cytokines and chemokines — chemicals that are released as part of the inflammatory process in rheumatoid arthritis.
Researchers were interested in looking at the relationship between disease activity in rheumatoid arthritis — as well as the levels of specific cytokines and chemokines — and the risk of developing diabetes. When looking at different cytokines and chemokines, the researchers controlled for factors that might affect levels of these chemicals as well as diabetes risk, such as age, sex, race, smoking status, body-mass index (BMI, a measure of body weight that takes height into account), and use of medications.
During a total of 9,223 person-years (an average follow-up period of about five years), 130 participants were diagnosed with diabetes. A number of factors were found to increase the risk of developing diabetes, including higher rheumatoid arthritis disease activity, being obese, older age and being a male. Currently smoking and taking the arthritis drug methotrexate were tied to a lower risk of developing diabetes.
In addition, the researchers found that several specific cytokines and chemokines were independently associated with a higher risk of developing diabetes — meaning that they were tied to diabetes risk regardless of rheumatoid arthritis disease activity.
Targeted treatments to help prevent diabetes?
This study highlights the role inflammation appears to play in the development of diabetes, with several specific chemicals involved in the body’s inflammatory response tied to diabetes risk. But it doesn’t explain why, exactly, diabetes develops in response to inflammation. This is an area that many researchers are eager to explore, and it may someday yield preventive therapies that reduce a person’s diabetes risk.
This study’s results suggest that one area of interest for future research may be the role of cytokines and chemokines in the development of diabetes, as well as potential therapies to reduce or block the effects of these chemicals.
In the meantime, it’s clear that effectively treating rheumatoid arthritis — by limiting disease activity as much as possible, and especially by using the drug methotrexate — is critical to reducing the risk of developing diabetes in people with this inflammatory disease. More studies are needed to determine whether other inflammatory conditions, including other forms of arthritis, are also associated with a higher risk of developing diabetes.
Want to learn more about inflammation? Read our definition, the see “Put Out the Fire of Diabetes Inflammation.”