Abstract: Objectives: In patients with rheumatoid arthritis (RA), insulin resistance (IR), a component of the metabolic syndrome, is closely linked to the systemic inflammation induced by proinflammatory cytokines such as tumor necrosis factor-? and interleukin (IL)-6. In the present study, we aimed to assess if an intravenous administration of the anti-IL-6 receptor tocilizumab may yield a rapid improvement of IR in RA. Methods: 50 consecutive non-diabetic patients with RA refractory to methotrexate, undergoing periodic treatment with tocilizumab, were studied. Besides disease activity, serum insulin, insulin/glucose ratio, insulin resistance (HOMA-IR) and insulin sensitivity (QUICKI) indexes were assessed immediately before and 1 hour after the end of an intravenous administration of tocilizumab (given in saline solution over 60 minutes). Results: When comparing baseline data (immediately before) and 1 hour after finishing tocilizumab administration, we observed a dramatic decrease of the serum insulin levels and insulin/glucose ratio. Also, a statistically significant reduction of IR (HOMA-IR: mean± standard deviation immediately before: 2.62±2.03 vs. 1.65±1.15 1 hour after the end of the infusion (p<0.01) and a statistically significant increase of insulin sensitivity (QUICKI immediately before 0.34±0.03 vs. 0.37±0.04 1 hour after the end of tocilizumab infusion (p<0.01) was observed. Conclusions: The intravenous administration of tocilizumab yields a rapid beneficial effect on IR and insulin sensitivity in non-diabetic RA patients. These findings support the potential beneficial effect of the IL-6 blockade on the mechanisms associated with the development of metabolic syndrome and cardiovascular disease in patients with RA.

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