AUTHOR=Ma Chifa , Liu Yiwen , He Shuli , Zeng Jingbo , Li Pingping , Ma Chunxiao , Ping Fan , Zhang Huabing , Xu Lingling , Li Wei , Li Yuxiu 

TITLE=C-Peptide: A Mediator of the Association Between Serum Uric Acid to Creatinine Ratio and Non-Alcoholic Fatty Liver Disease in a Chinese Population With Normal Serum Uric Acid Levels

JOURNAL=Frontiers in Endocrinology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2020.600472

DOI=10.3389/fendo.2020.600472

ISSN=1664-2392

ABSTRACT=<sec><title>Background</title><p>The data on the relationship between normal-ranged serum uric acid (SUA), β-cell function, and non-alcoholic fatty liver disease (NAFLD) are complicated and insufficient. Moreover, uric acid is excreted by kidney, and SUA levels may be affected by renal function. Thus, we introduced a renal function-normalized index [serum uric acid to creatinine ratio (SUA/Cr)] into the study and explored the association between SUA/Cr, C‐peptide and NAFLD in a Chinese population with normal SUA levels by a cross-sectional analysis.</p></sec><sec><title>Materials and Methods</title><p>A total of 282 individuals with normal SUA levels and different glucose tolerance status from a diabetes project were included in the study (mean age = 53.7± 10.5 years; women = 64.50%). NAFLD was diagnosed by abdominal ultrasonography (NAFLD, n=86; without NAFLD, n=196). Trapezoid formula was used to calculate area under the curve of C‐peptide (AUC<sub>CP</sub>) from 4 points (including 0, 30,60, and 120min) during 2-h oral glucose tolerance test. Spearman correlation analysis was used to explore the correlation between SUA/Cr, AUC<sub>CP</sub> and NAFLD risk factors. Multiple logistic regression analysis was used to explore the association between SUA/Cr or AUC<sub>CP</sub> and NAFLD. Mediation analysis was used to explore whether AUC<sub>CP</sub> mediated the association between SUA/Cr and NAFLD.</p></sec><sec><title>Results</title><p>Individuals with NAFLD had significantly higher SUA/Cr and AUC<sub>CP</sub> than those without NAFLD(P&lt;0.05). Spearman correlation analysis showed that both SUA/Cr and AUC<sub>CP</sub> were significantly associated with many NAFLD risk factors, and SUA/Cr was positively correlated with AUC<sub>CP</sub> (P&lt;0.05). Multiple logistic regression analysis indicated that SUA/Cr and AUC<sub>CP</sub> were positively associated with NAFLD incidence (P&lt;0.05). Medication analysis indicated that SUA/Cr had a significant direct effect on NAFLD (β =0.5854, 95% CI: 0.3232–0.8966), and AUC<sub>CP</sub> partly mediated the indirect effect of SUA/Cr on NAFLD incidence (β =0.1311, 95% CI: 0.0168–0.4663).</p></sec><sec><title>Conclusions</title><p>SUA/Cr was positively associated with NAFLD incidence, and AUC<sub>CP</sub> partly mediated the association in a Chinese population with normal SUA levels. Thus, we should pay more attention to high-normal SUA and C-peptide levels due to their predictive power in NAFLD incidence.</p></sec>