Insulin resistance in rheumatoid arthritis: relationship to lipid metabolism disorders and metabolic syndrome

Abstract

Objective:to determine the incidence of insulin resistance (IR) in patients with rheumatoid arthritis (RA) and to assess the relationship of IR to blood lipid profile changes and the presence of metabolic syndrome (MS).Subjects and methods.The investigation enrolled 47 RA patients (41 women and 6 men) without a history of diabetes mellitus (DM) and with normal fasting glucose levels during examination. The patients' median age was 56 [39; 62] years; disease duration – 6 [5; 14] years. Most of the patients had low (40.4%) or moderate (42.6%) RA activity (DAS28). IR was diagnosed using the Homeostastic Model Assessment of Insulin Resistance (HOMA-IR) index 2.77. The presence of MS was assessed by the National Cholesterol Education Program/Adult Treatment Panel III (NCEP/ATPIII) criteria and the International Diabetes Federation (IDF) criteria.Results and discussion.The median HOMA-IR value in RA patients was 1.7 [1.1; 3.2]. The HOMA-IR index correlated with age (r=0.3; p=0.04), body mass index (r=0.6; p<0.001), waist circumference (r=0.6; p<0.001), and the concentrations of total cholesterol (r=0.3; p=0.02) and triglycerides (TG) (r=0.5; p<0.001). All the patients were divided into two groups: 1) 15 patients with IR; 2) 32 patients without IR. The patients of both groups were matched for sex, age, RA duration and activity, and therapy, but the RA patients with IR more often had abdominal obesity (100.0 and 37.5%), hypertriglyceridemia (33.3 and 6.3%) and the atherogenic index >3.0 (40.0 and 6.3%, respectively; p<0.05 in all cases). MS was diagnosed using the NCEP/ATPIII criteria in 46.7% of cases with RI and in 6.3% of those without IR; MS was identified by the IDF criteria in 60.0 and 12.5% of cases, respectively (p<0.01 in all cases). There were no differences between groups in the incidence of hypertension, myocardial infarction, or in the frequency of surgeries for myocardial revascularization.Conclusion.More than 30% of RA patients without DM have IR (HOMA-IR ≥2.77). IR in RA is associated with obesity, elevated blood TG levels, and a proatherogenic lipid profile. The use of the criteria for MS could not always allows suspect IR in patients with RA.