Insulin resistance in rheumatoid arthritis: Disease related indicators and associations with the presence and progression of subclinical atherosclerosis

Jon T Giles, et al.

Background Systemic inflammation and insulin resistance (IR) are linked, yet the determinants of IR and the impact of IR on atherosclerosis are incompletely understood in rheumatoid arthritis (RA).

Methods IR, estimated using the homeostatic model (HOMA-IR), was compared between RA patients and a group of demographically matched non-RA controls. Differences in the associations of HOMA-IR with the Agatston coronary arterial calcium (CAC) score and ultrasound-determined intima-medial thickness (IMT) of the common (CCA) and internal carotid arteries (ICA), and focal plaque in the ICA/carotid bulb were compared by RA status.

Results Among the 195 RA and 198 controls studied, average HOMA-IR levels were higher in the RA group by 31%, and were consistently higher in the RA group regardless of strata of demographic or cardiometabolic risk factors. While HOMA-IR was strongly and significantly associated with C-reactive protein (CRP) and IL-6 in the control group, the association was weaker in the RA group. Among RA patients, higher HOMA-IR was associated with rheumatoid factor (RF) seropositivity in men and women, and prednisone use in women only. Pre-adjustment, higher HOMA-IR was associated with all assessed subclinical atherosclerosis measures in the control group only. Associations were diminished and lost statistical significance after adjusting for cardiovascular risk factors. Among the RA patients, neither baseline nor average HOMA-IR was significantly associated with change in any of the atherosclerosis measures over an average of 3.2 years of follow-up.

Conclusions Although IR was higher in RA than in non-RA controls, higher levels may not independently impart additional atherosclerosis risk. This article is protected by copyright. All rights reserved.