Insulin resistance in non-diabetes patients with spondyloarthritis.

Objectives: Insulin resistance (IR) constitutes a major underlying abnormality driving cardiovascular disease in the general population and has been linked to inflammatory diseases. In this study, we aimed to determine the prevalence of IR in patients with spondyloarthritis (SpA) and whether IR can be explained by disease-related features in such cases. Method: The study included 577 subjects: 306 patients diagnosed with SpA according to Assessment of SpondyloArthritis international Society criteria and 271 controls. Insulin and C-peptide serum levels, IR and ß-cell function (%B) indices by homoeostatic model assessment (HOMA2), and lipid profiles were assessed in patients and controls. A multivariable regression analysis was performed to evaluate the differences in IR indices between patients and controls and to determine how IR is associated with disease-related characteristics in SpA patients. Results: HOMA2-%B and HOMA2-IR scores, both calculated with insulin or C-peptide, had significantly higher values in SpA patients compared to controls in multivariable analysis adjusted for age, gender, traditional IR-related factors, and glucocorticoid intake. Disease activity, functional status, and metrological SpA indices were positively related to IR, but only in univariable analysis. Disease duration and positivity for human leucocyte antigen-B27 were independently associated with a higher HOMA2-%B after multivariable analysis. Conclusion: Patients with SpA have an increased IR compared to controls. SpA disease-related data are independently associated with ß-cell dysfunction.

Systemic blockade of TNF-α does not improve insulin resistance in humans.

The purpose of this study was to determine whether long-term modulation of inflammatory activity by tumor necrosis factor (TNF)-α inhibitors has some influence on insulin resistance (IR). 16 active rheumatoid arthritis (RA) patients without CV risk factors treated with anti-TNF-α agents were included in this study. RA activity by disease activity score 28, IR by HOMA2-IR, body composition by impedance analysis, physical activity by accelerometry, abdominal fat distribution by magnetic resonance imaging, and serum level of key adipokines by ELISA were measured at baseline and during a 1-year follow-up period. Patient body mass index increased significantly (26.94 ± 3.88 vs. 28.06 ± 4.57 kg/m2, p=0.02) after 1 year of treatment. Body composition, in terms of fat and fat-free mass, remained unchanged except for a significant elevation in body cell mass (25.50 ± 4.60 vs. 26.60 ± 3.17 kg, p=0.02). Basal levels of IR in the RA patients included in this study were significantly higher than healthy controls (1.6 ± 0.8 vs. 1.11 ± 0.56, p=0.011) but did not change during the follow-up. Nor did basal concentrations of adiponectin, visfatin, leptin, ghrelin, resistin, and apelin in response to anti-TNF-α treatment; only retinol-binding protein 4, showed a significant increase (51.7 ± 32.7 vs. 64.9 ± 28.4 µg/ml, p=0.03) at the end of the study. IR, adiposity distribution, and serum levels of most adipokines are not significantly affected by long-term inhibition of TNF-α in RA patients. Our data suggest that although systemic blockade of TNF-α exerts an anticachectic effect in RA patients, it does not seem to play a major role in IR.