Abdominal fat deposits determined by magnetic resonance imaging in relation to leptin and vaspin levels as well as insulin resistance in the general adult population

BACKGROUND: Various fat depots including visceral (VAT), subcutaneous adipose tissue (SAT) or liver fat content (LFC) were supposed to have different influences on various entities including adipokine levels as well as insulin resistance/sensitivity. Therefore, the aim of the study was to investigate the associations of SAT, VAT and LFC with the levels of leptin and vaspin as well as insulin resistance in a general non-diabetic population. METHODS: In total, 1825 participants of the Study of Health in Pomerania were characterized according to body fat compartments and LFC determined by magnetic resonance imaging. Of those subjects, insulin resistance (HOMA-IR) and insulin sensitivity ([ ISI (comp)) were determined in 981 participants and adipokines were assessed in 698 using enzyme-linked immunosorbent assay. Analyses of variance and linear regression models adjusted for age, sex, smoking, height, physical inactivity and alcohol consumption were used for analysis. RESULTS: Using the residual method to assess independently the effect of the various fat depots, a strong positive association of SAT (beta per standard deviation (s. d.) increase 0.54 (95% confidence interval (CI) 0.47-0.60)) but not VAT (beta 0.01 (95% CI -0.08 to 0.09)) and LFC (beta 0.01 (95% CI -0.06 to 0.08)) with log2-leptin levels was found independent of the HOMA-IR status. Moreover, a positive association of LFC (beta 0.17 (95% CI 0.07-0.26)) with log2-vaspin levels becomes apparent, which were mostly driven by subjects with a low HOMA-IR. With respect to HOMA-IR and ISI(comp) index, pronounced positive and inverse associations to all fat markers were revealed, respectively, with the strongest relation found for SAT and LFC. CONCLUSIONS: SAT and LFC were identified as predominant sites associated with leptin and vaspin levels, respectively. Residual analysis pointed towards a general adverse effect of disproportional triglyceride storage across physiological despots, in particular in ectopic sides such as the liver, with markers of insulin resistance.