Associations between serum clusterin levels and non-alcoholic fatty liver disease

Objective: Clusterin is closely correlated with insulin resistance and its associated comorbidities. This study aimed to investigate the correlation between serum clusterin levels and non-alcoholic fatty liver disease (NAFLD) and further explore the mediating role of insulin resistance in this relationship. Methods: This study enrolled 195 inpatients (41 males and 154 females) aged 18-61 years. Twenty-four patients were followed up for 12 months after bariatric surgery. Serum clusterin levels were measured using a sandwich enzyme-linked immunosorbent assay. Fatty liver disease was diagnosed on the basis of liver ultrasonography. The fatty liver index (FLI) was calculated to quantify the degree of hepatic steatosis. The mediating role of homeostasis model assessment-insulin resistance (HOMA-IR) was assessed using mediation analysis. Results: Participants with NAFLD had significantly higher serum clusterin levels than those without NAFLD (444.61 (325.76-611.52) mg/L vs 294.10 (255.20-373.55) mg/L, P < 0.01). With increasing tertiles of serum clusterin levels, the prevalence of NAFLD displayed an upward trend (P < 0.01). Multivariate linear regression analysis showed that serum clusterin levels were a positive determinant of FLI (standardized & beta; = 0.271, P < 0.001) after adjusting for multiple metabolic risk factors. Serum clusterin levels significantly decreased after bariatric surgery (298.77 (262.56-358.10) mg/L vs 520.55 (354.94-750.21) mg/L, P < 0.01). In the mediation analysis, HOMA-IR played a mediating role in the correlation between serum clusterin levels and FLI; the estimated percentage of the total effect was 17.3%. Conclusion: Serum clusterin levels were associated with NAFLD. In addition, insulin resistance partially mediated the relationship between serum clusterin levels and FLI.