Preliminary research suggests that use of the anti-malarial drug hydroxychloroquine may help reduce the risk of the development of diabetes in patients with rheumatoid arthritis, according to a study in the July 11 issue of JAMA.Type 2 diabetes mellitus affects nearly 8 percent of US adults, and its prevalence has been increasing. Antimalarials such as hydroxychloroquine, a long-standing safe and inexpensive treatment for an autoimmune disease such as rheumatoid arthritis, theoretically may improve glucose tolerance and prevent diabetes mellitus, according to background information in the article. In vitro and animal studies indicate that antimalarials improve insulin secretion and peripheral insulin sensitivity.