Resistin is not associated with insulin sensitivity or the metabolic syndrome in humans

Aims/hypothesis: The aim of this study was to further elucidate the relationship between resistin and insulin sensitivity, body fat distribution and the metabolic syndrome in humans. Methodds: We measured plasma resistin levels in 177 non-diabetic subjects (75 male, 102 female; age 32-75 years). BMI, waist circumference, blood pressure, lipids, glucose, plasminogen-activator inhibitor 1 (PAI-1), adiponectin and leptin levels were also measured. The insulin sensitivity index (S-I) was quantified using Bergman's minimal model. Intra-abdominal fat (IAF) and subcutaneous fat (SQF) areas were quantified by CT scan. Presence of metabolic syndrome criteria was determined using the National Cholesterol Education Program Adult Treatment Panel III guidelines. Results: When subjects were divided into categories based on BMI (< or >= 27.5 kg/m(2)) and S-I (< or >= 7x10(-5) min(-1) [pmol/l](-1)), resistin levels did not differ between the lean, insulin-sensitive (n=53, 5.36 +/- 0.3 ng/ml), lean, insulin-resistant (n=67, 5.70 +/- 0.4 ng/ml) and obese, insulin-resistant groups (n=48, 5.94 +/- 0.4 ng/ml; ANOVA p=0.65). Resistin correlated with age (r=-0.22, p < 0.01), BMI (r=0.16, p=0.03) and SQF (r=0.19, p=0.01) but not with S-I (p=0.31) or IAF (p=0.52). Resistin did not correlate with the number of metabolic syndrome criteria or any of the individual metabolic syndrome criteria. In contrast, adiponectin, PAI-1 and leptin each correlated with IAF, SQF and S-I. Additionally, the number of metabolic syndrome criteria correlated with adiponectin (r=-0.32, p < 0.001), leptin (r=0.31, p < 0.001) and PAI-1 (r=0.26, p=0.001). Conclusions/interpretation: In contrast to other adipokines, resistin is only weakly associated with body fat and is unlikely to be a major mediator of insulin resistance or the metabolic syndrome in humans.