Background: Bilirubin has got a potential anti-oxidant, anti-inflammatory and cytoprotective effect. It has been shown that its concentration is inversely related to cardiometabolic diseases. Recent studies have revealed the association between serum bilirubin concentrations and metabolic syndrome (MS) among children and adolescents in U.S. and among Korean adults. The aim of this study was to evaluate the association of total serum bilirubin level with MS and insulin resistance in Poland.
Methods: We examined 1568 patients aged 18 to 93 years. The tested population was a nationally representative sample of Polish adults. They were derived from cross-sectional study, when serum total bilirubin level and risk factors of cardiovascular diseases were determined.
Results: The prevalence of MS in bilirubin level quartiles (95% CI in parentheses) was 28.9% (24.5%-33.3%), 32.6% (28.3%-36.9%), 23.4% (19.0%-27.8%), 21.8% (17.5%-26.2%) respectively for quartiles 1-4 (p = 0.002) The multivariate analysis showed odds ratio for MS in third and fourth quartile of bilirubin level equal to 0.70 (0.50-0.99) and 0.68 (0.48-0.95) respectively in comparison to the lowest quartile. The more criteria of metabolic syndrome were fulfilled by the patient, the lower was mean total bilirubin level (p = 0.012). In study group there was also a strong, independent association of bilirubin level with fasting insulin level and insulin resistance (HOMA-IR). The odds ratio of insulin resistance was 0.53 (0.38-0.74) for the fourth quartile in reference to the lowest quartile of bilirubin.
Conclusion: In Polish adults serum total bilirubin level is inversely related to the prevalence of MS and insulin resistance.