DESTIN, FLA. — The prevalence of metabolic syndrome is increased in patients with rheumatoid arthritis, compared with the general population, as is the prevalence of insulin resistance, data from numerous studies show.
Likewise, insulin resistance is increased in those with systemic lupus erythematosus, and the increased risks are independent of age, sex, race, body mass index, and corticosteroid use. These findings suggest that inflammation plays a role in the development of insulin resistance and other components of metabolic syndrome, although the mechanisms in the two diseases differ, Dr. C. Michael Stein reported at a rheumatology conference sponsored by Virginia Commonwealth University, Richmond.
For example, in a study in press at the time of Dr. Stein's presentation, the prevalence of insulin resistance was nearly 60% in patients with long-standing rheumatoid arthritis, and about 50% in those with early rheumatoid arthritis, compared with about 20% in controls. In a published study of lupus patients, more than 30% had insulin resistance, compared with about 11% of controls (Ann. Rheum. Dis. 2007;66:208-14).
However, interleukin-6 levels have been shown to be significantly associated with insulin resistance in rheumatoid arthritis, (rho 0.63; P less than.001), but not in lupus (rho 0.16; P = .18), and the same has been shown to be true for tumor necrosis factor-α (rho 0.50; P less than .001and rho 0.11; P = .24, respectively), said Dr. Stein of Vanderbilt University, Nashville, Tenn.
Body mass index traditionally is an important factor in the metabolic syndrome pathway to coronary heart disease, and was significantly associated with insulin resistance in lupus in the study (rho 0.54; P less than .001), but it appears that inflammation also can lead to the same pathway, he explained.
In addition, atherosclerosis is accelerated in both diseases. This also may be a factor of inflammation, as well as of insulin resistance and metabolic syndrome. It does not appear, in these diseases, to be associated with traditional cholesterol/lipid concentration-related mechanisms, Dr. Stein noted.
“The good news is that the features of metabolic syndrome can be reversed,” he said.
The same lifestyle interventions recommended for other patients with metabolic syndrome are recommended for those with rheumatoid arthritis or lupus. As for the potential for treatments that target the inflammatory mediators of these diseases to have a beneficial effect on insulin resistance and metabolic syndrome, he said, research is underway.