Background— Anti-inflammatory and proinflammatory molecules purportedly play an important role in developing metabolic syndrome (MetS). However, little is known as to the relative importance of these molecules in the association with MetS.

Methods and Results— We studied 624 middle-aged Japanese men without medical history of cardiovascular disease or cancer and investigated the associations of circulating tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), C-reactive protein (CRP), and adiponectin with MetS. We used the respective definitions proposed by the National Cholesterol Education Program Adult Treatment Panel III (ATP-III), the International Diabetes Federation, and the Japanese Society of Internal Medicine. Decreased serum adiponectin was observed in those with any of the ATP-III–MetS components, whereas this was not the case with increased TNF-α, IL-6, or CRP. Adiponectin and CRP levels linearly deteriorated with an increasing number of ATP-III–MetS components (trend P<0.001, respectively). Significantly higher CRP and lower adiponectin levels were observed in those who met any MetS criteria, whereas increased TNF-α was observed in only those with ATP-III–MetS. Finally, odds ratios (ORs) for MetS prevalence of a 1-SD increase/decrease in log-transformed 4 markers were calculated with multivariate logistic regression analyses. Consequently, decreased adiponectin was associated most strongly with ATP-III–MetS (adiponectin: OR, 1.90 [95% CI, 1.44 to 2.51]; P<0.001; CRP: OR, 1.33 [95% CI, 1.01 to 1.74]; P=0.03; TNF-α: OR, 1.25 [95% CI, 0.94 to 1.67]; P=0.12; and IL-6: OR, 0.87 [95% CI, 0.63 to 1.19]; P=0.37). This result was not altered by using the other 2 criteria.

Conclusions— The present results raise the possibility that decreased serum adiponectin might be fundamentally involved in the development of MetS.