Effects of infliximab treatment on insulin resistance in patients with rheumatoid arthritis and ankylosing spondylitis.

BACKGROUND Tumour necrosis factor alpha (TNFalpha) may be an important mediator of insulin resistance. Infliximab is a chimeric monoclonal, high affinity antibody against the soluble and transmembrane TNFalpha, which can reduce markedly the biological activity of circulating and tissue TNFalpha and is used to treat various autoimmune disorders. OBJECTIVE To assess the effects of infliximab infusions on insulin sensitivity in patients with rheumatoid arthritis (RA) and ankylosing spondylitis (AS). METHODS 45 patients (28 with RA, 17 with AS) aged 19-74 years were studied. All patients were treated with intravenous infliximab. A complete biochemical profile was obtained before and after 6 months' treatment with infliximab. The Homoeostasis Model Assessment (HOMA) Index was used to measure insulin resistance and the Quantitative Insulin Sensitivity Check Index (QUICKI) to measure insulin sensitivity. RESULTS In the whole study group, no significant changes of the HOMA Index or QUICKI were seen. In the tertile of patients with the highest insulin resistance, a significant decrease of the HOMA Index and increase of the QUICKI was found (p<0.01 for both). CONCLUSIONS The results suggest that infliximab treatment may have beneficial effects on insulin sensitivity in the most insulin resistant patients with RA and AS.