correlation of liver fat content with serum vitamin a level and insulin resistance in patients with nonalcoholic fatty liver disease

ObjectiveTo investigate the correlation of liver fat content (LFC) with serum vitamin A (VA) level and insulin resistance (IR) in patients with nonalcoholic fatty liver disease (NAFLD). MethodsA total of 200 patients with an initial diagnosis of NAFLD in Shanghai Chongming from February 2016 to January 2017 were enrolled. According to the results of oral glucose tolerance test with 75 g glucose and insulin releasing test, NAFLD patients were divided into simple NAFLD group with 91 patients, NAFLD-impaired glucose regulation (IGR) group with 69 patients, and NAFLD-type 2 diabetes mellitus (T2DM) group with 40 patients. A total of 98 healthy volunteers were enrolled as healthy control group. The homeostasis model was used to evaluate IR, high-performance liquid chromatography was used to measure serum VA level, and 3.0 T 1H-magnetic resonance spectroscopy was used to measure LFC. A one-way analysis of variance was used for comparison of normally distributed continuous data between multiple groups, and the LSD-t-test was used for further comparison between two groups; the Kruskal-Wallis H test was used for comparison of non-normally distributed continuous data between multiple groups, and the Mann-Whitmey U test was used for further comparison between two groups. The Pearson′s chi-squared test was used for comparison of categorical data between groups. A Spearman correlation analysis was also performed. ResultsThere were significant differences in fasting plasma glucose (FPG), 2-hour postprandial glucose (2hPG), and HbAlc between the healthy control group, simple NAFLD group, NAFLD-IGR group, and NAFLD-T2DM group (F=303.8，133.1, and 249.3, all P＜0.01). The simple NAFLD group, NAFLD-IGR group, and NAFLD-T2DM group had significant increases in FPG, 2hPG, and HbAlc (all P＜0.01), and compared with the simple NAFLD group, NAFLD-IGR group, and NAFLD-T2DM group, the healthy control group had significant reductions in body mass index, alanine aminotransferase, triglyceride, and low-density lipoprotein (all P＜0.01). The simple NAFLD group, NAFLD-IGR group, and NAFLD-T2DM group had significantly higher serum VA level, LFC, and HOMA2-IR than the healthy control group (F=9.2, H=216.1, and H=151.0, all P＜0.01). HOMA2-IR and LFC gradually increased in the simple NAFLD group, NAFLD-IGR group, and NAFLD-T2DM group (H=26.7 and 38.6, both P＜0.01). There were significant differences in HOMA2-IR and LFC between the NAFLD-IGR group and the NAFLD-T2DM group (U=995 and 800, both P＜0.01); there were also significant differences in HOMA2-IR, LFC, and VA between the NAFLD-IGR group and the simple NAFLD group, as well as between the NAFLD-T2DM group and the simple NAFLD group (all P＜0.05). LFC was positively correlated with VA (R2=0.103, P＜0.001) and HOMA2-IR (R2=0.531, P＜0.001). ConclusionThe increase in LFC is closely associated with high serum VA level and disorder of glucose metabolism in patients with NAFLD.