TNF-alpha antagonist therapy improves insulin sensitivity in non-diabetic ankylosing spondylitis patients

Objectives Since insulin resistance can promote endothelial dysfunction, and anti-TNF-alpha treatment improves endothelial function in ankylosing spondylitis (AS) patients, in the present study we sought to assess whether an infusion of the anti-TNF-alpha 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 +/- 9.04) were compared (p=0.004). Conclusion 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.