Inflammatory markers in relation to insulin resistance and the metabolic syndrome

Inflammation has repeatedly been demonstrated to be associated with the metabolic syndrome (MetS) and insulin resistance, but the relative importance of different aspects of the inflammatory process is largely unexplored.

We measured circulating interleukins (IL-1alpha, IL-1beta, IL-2, IL-4, IL-6, IL-8, IL-10); other cytokines (tumour necrosis factor-alpha, interferon gamma and monocyte chemotactic protein-1), cell adhesion molecules [vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1, E-selectin, P-selectin, l-selectin], and systemic inflammation markers [C-reactive protein (CRP) and leukocyte count] in 943 70 year old participants (50% women) of the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. We related these biomarkers to MetS and the homeostasis model assessment insulin resistance index (HOMA-IR).

In a multivariable model including all inflammatory markers conjointly together with sex, log VCAM-1 [odds ratio (OR), 1.45; 95% confidence interval (CI), 1.22-1.72 per 1 SD increase; P < 0.0001], log E-selectin (OR, 1.33; 95% CI, 1.12-1.57 per 1SD increase; P = 0.001), and log CRP (OR, 1.41; 95% CI, 1.20-1.66 per 1-SD increase; P < 0.0001) were independently associated with MetS. These biomarkers were also independently associated with HOMA-IR.

Among 17 inflammatory biomarkers, most of them previously not examined in relation to MetS and insulin resistance, VCAM-1, E-selectin and CRP demonstrated the strongest associations with MetS and insulin resistance in our community based sample of the elderly. The relative importance of these biomarkers in predicting the development of MetS, insulin resistance and cardiovascular disease needs to be further examined in a longitudinal setting.