TUESDAY, June 21, 2011 (HealthDay News) -- Some medications commonly used to treat rheumatoid arthritis and psoriasis may help patients with these autoimmune disorders lower their risk of developing diabetes, researchers say.
New research found that a particular class of disease-modifying antirheumatic drugs (DMARDs) known as tumor necrosis factor (TNF) inhibitors and the antimalarial drug hydroxychloroquine can reduce diabetes risk by 38 percent and 46 percent, respectively, in people with rheumatoid arthritis or psoriasis.
"If you have rheumatoid arthritis or psoriasis, you may be at an increased risk of diabetes, and a number of different antirheumatic drugs may reduce your future risk of diabetes," said study author Dr. Daniel Solomon, chief of clinical science in rheumatology at Brigham and Women's Hospital in Boston.
However, Solomon was quick to point out that this was an observational study, and does not prove a cause-and-effect relationship between taking these medications and a reduced risk of diabetes. He said that for people who already have to take these drugs for other conditions, this research shows that there may be an added benefit with taking some of them.
The findings are published in the June 22/29 issue of the Journal of the American Medical Association.
Using statistics from two large health insurance company databases -- one in Canada and one in the United States -- the researchers reviewed data on people who had either rheumatoid arthritis or psoriasis. From a group of 121,280, the researchers immediately excluded the 12,996 who already had a diabetes diagnosis.
"These patients are at high risk of type 2 diabetes. This study found that about 10 percent already have it, which is higher than would be expected in the general population," said Dr. Joel Zonszein, director of the clinical diabetes program at Montefiore Medical Center in New York City.
The investigators then looked for those who had a prescription for at least one of the medications used for these conditions, and found that 13,905 were taking at least one of these drugs. The researchers further divided the group into four subgroups: those taking TNF inhibitors with or without other DMARDs; people taking methotrexate without a TNF inhibitor or hydroxychloroquine; hydroxychloroquine without TNF inhibitors or methotrexate; or other DMARDs without TNF inhibitors, methotrexate or hydroxychloroquine.
The study found that the rate of diabetes diagnoses over 12 years was 19.7 per 1,000 person-years for TNF inhibitors, 22.2 for hydroxychloroquine, 23.8 for methotrexate and 50.2 for other DMARDs. Compared to the other DMARDs, this translates to a reduced risk of 38 percent for TNF inhibitors, 23 percent for methotrexate and 46 percent for hydroxychloroquine.
Solomon said in an adjusted analysis, hydroxychloroquine and TNF inhibitors were the two types of drugs that appeared to make a significant difference in diabetes risk. These drugs are sold under brand names such as Plaquenil (hydroxychloroquine) and Enbrel, Humira and Remicade (TNF inhibitors).
Solomon said the reason these drugs might be protective isn't known, but the researchers suspect they reduce inflammation, which reduces insulin resistance and diabetes.
"Careful treatment of inflammatory conditions may reduce your future risk of diabetes," Solomon added.
"In a population with a very high incidence of diabetes, some medications may prevent or slow down the process of type 2 diabetes," said Zonszein.
Both experts added that these medications may have significant side effects. In addition, they can be expensive.
"The question is always, 'Is it worth giving these drugs?' You may prevent diabetes, but in doing so, will you create other problems?" said Solomon, who added that the information from this study might be helpful in selecting one treatment regimen over another for people with rheumatic diseases.
Learn more about rheumatoid arthritis and disease-modifying antirheumatic drugs (DMARDs) from the U.S. National Institute of Arthritis and Musculoskeletal and Skin Diseases. They also have more information on psoriasis.