Levels of adiponectin, C-reactive protein and interleukin-1 receptor antagonist are associated with insulin sensitivity: a population-based study.

Background: We evaluated the relationship of insulin sensitivity (assessed with the quantitative insulin sensitivity check index, QUICKI) to adiponectin and pro-inflammatory markers, levels of high-sensitivity C-reactive protein (hs-CRP) and interleukin-1 receptor antagonist (IL-1 Ra).

Methods: Cross-sectional study. Study population (N=923, i.e 411 men and 512 women) included five different population-based age groups (born in 1942, 1947, 1952, 1957 and 1962), [mean age 46 years and mean body mass index (BMI) 26 kg/m(2)]. Study protocol included an interview and measurements of anthropometric parameters and glucose, insulin, adiponectin, hs-CRP and IL-1 Ra.

Results: Correlation (r) between QUICKI and adiponectin level was 0.334 [95% confidence intervals (CI), 0.275-0.392] and partial correlation adjusted for gender, BMI, smoking status, physical activity and age was 0.247 (95% CI, 0.185-0.308). There was negative correlation between QUICKI and IL-1 Ra (r= -0.385; 95% CI, -0.440 to -0.328) which remained statistically significant after the adjustment for confounding factors (r= -0.178; 95% CI, -0.240 to -0.113). Similarly, QUICKI was negatively correlated with hs-CRP (r= -0.241; 95% CI, -0.302 to -0.178), but after the adjustment it lost its statistical significance. There was a statistically significant gender difference (p=0.018) in correlation between QUICKI and IL-1 Ra levels (men: r= -0.348; 95% CI, -0.436 to - 0.261; women r= -0.500; 95% CI, -0.537 to -0.398).

Conclusions: Our results show that adiponectin level and markers of low-grade inflammation are related to insulin sensitivity. Adiponectin and IL-1 Ra levels might be better markers of the risk of obesity and type 2 diabetes than hs-CRP.