Objectives: Since insulin resistance can promote endothelial dysfunction, and anti-TNF-α treatment improves endothelial function in ankylosing spondylitis (AS) patients, in the present study we sought to assess whether an infusion of the anti-TNF-α monoclonal antibody-infliximab may improve insulin sensitivity in non-diabetic AS patients.
Methods: We assessed a series of 30 non-diabetic patients with AS attending hospital outpatient clinics who fulfilled the modified New York diagnostic criteria for AS. In all cases, the drug was given as an intravenous infusion in a saline solution over 120 minutes. Fasting blood samples were taken for determination of plasma glucose and serum insulin levels immediately before (time 0) and after infliximab infusion (time 120).
Results: At the time of the study only 8 (26.7%) of the 30 patients fulfilled definitions for insulin resistance as HOMA index was in most cases less than 2.29. Nevertheless, a statistically significant reduction in the HOMA values was observed when results found at time 0 (mean±SD: 1.72±1.22) were compared with those observed immediately after infliximab infusion (1.18±0.94) (p<0.001). The reduction in HOMA values was more important in those patients with the higher values of HOMA before infliximab infusion. Also, a significant improvement of insulin sensitivity was observed in most patients when QUICKI values before (0.37±0.04) and after infusion (0.39±0.04) were compared (p=0.004).
Conclusions: The present study shows that non-diabetic patients with AS on treatment with infliximab experience a rapid improvement of insulin sensitivity following administration of this drug.