Associations of Adiponectin with Body Fat Distribution and Insulin Sensitivity in Nondiabetic Hispanics and African-Americans

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Abstract
Context: Hypoadiponectinemia has emerged as an independent risk factor for type 2 diabetes and cardiovascular disease. Although associations of adiponectin with central obesity and insulin resistance have been reported, very little data are available from studies using detailed measures of insulin sensitivity (SI) and/or body fat distribution in ethnic groups at high risk for metabolic disease. Objective: The aim of the study was to identify the correlates of adiponectin in 1636 nondiabetic Hispanics and African-Americans. Design: A cross-sectional analysis of participants in the Insulin Resistance Atherosclerosis Family Study was conducted. SI was determined from frequently sampled iv glucose tolerance tests with minimal model analysis. Subcutaneous and visceral adipose tissues (SAT, VAT, respectively) were determined with computed tomography. Triglyceride, high-density lipoprotein, C-reactive protein, and adiponectin were measured in fasting samples. Generalized estimating equation (GEE) models were used to identify factors associated with adiponectin concentration. Setting: A multicenter study using a family-based design was conducted. Participants: A total of 1636 nondiabetic Hispanic and African-American subjects participated. Main Outcome Measures: Circulating adiponectin concentration was measured. Results: Age, female gender, high-density lipoprotein, SAT, and SI were positive independent correlates of adiponectin, whereas glucose, CRP, and VAT were negative independent correlates (all P < 0.05). Ethnicity was not an independent correlate of adiponectin in this model (P = 0.27); however, an ethnicity by VAT interaction term was retained, indicating a stronger negative association of VAT with adiponectin in African-Americans compared with Hispanics. Conclusion: Directly measured SI, VAT, and SAT were independently correlated with adiponectin in Hispanic and African-American subjects. The inverse association of VAT with adiponectin was stronger in African-Americans compared with Hispanics, a finding that suggests possible ethnic differences in the effects of visceral obesity.