Circulating visfatin level is correlated with inflammation, but not with insulin resistance

Recent studies, both in vitro and in vivo, have indicated that visfatin is one of the inflammatory cytokines, although the relationship between visfatin and insulin resistance remains inconclusive. Accordingly, we assessed the association between visfatin concentrations in serum and those of interleukin-6 (IL-6) and C-reactive protein (CRP), known as markers of systemic inflammation, and also investigated the relationship between these serum concentrations and insulin resistance.

A total of 295 Japanese Americans living in Hawaii (126 men and 169 women, mean age 68.7 +/- 14.9 years) were enrolled. The serum levels of visfatin, IL-6 and CRP levels were measured, and homeostasis model assessment for insulin resistance (HOMA-IR) was calculated as a marker of insulin resistance.

Significant positive correlations were found between serum levels of visfatin and IL-6 or CRP (r = 0.271, P < 0.001; r = 0.118, P < 0.05, respectively). Multiple regression analysis revealed that correlations between serum levels of visfatin and IL-6 or CRP remained significant after adjustments for age, sex, body mass index, per cent body fat and waist girth. There was no significant trend of the HOMA-IR for the tertiles of serum concentrations of visfatin. On the other hand, a significant trend towards increase of HOMA-IR with increasing tertile of serum concentrations, from the lowest to the highest, was observed for both IL-6 and CRP. The HOMA-IR in subjects with serum concentration of IL-6 or CRP in the highest or intermediate tertiles of IL-6 or CRP were significantly higher than that in subjects in the lowest tertile, even after adjustment for age and sex (IL-6: P < 0.001 and P < 0.001, respectively; CRP: P < 0.001 and P < 0.01, respectively).

Serum visfatin levels were positively correlated with the serum levels of IL-6 and slightly related with serum levels of CRP, but not with HOMA-IR, in Japanese Americans. Our results indicate that circulating visfatin may reflect inflammation status.