Sex differences in the association between adipose insulin resistance and non-alcoholic fatty liver disease in Chinese adults

BACKGROUND: Adipose insulin resistance (Adipo-IR) is associated with multiple metabolic diseases, including non-alcoholic fatty liver disease (NAFLD). The study aimed to evaluate sex differences in the association between Adipo-IR and NAFLD, and further investigated other potential modifiers. METHODS: This cross-sectional study enrolled adults without diabetes who underwent physical examinations in Beijing Chao-Yang Hospital. We calculated the Adipo-IR index as the product of the fasting insulin and free fatty acid concentration. We categorized Adipo-IR into four groups according to quartiles, using the first interquartile range (Q1) as the reference. Logistic regression was used stratified by the modifiers after adjustment for potential confounders. RESULTS: There were 5586 participants in the study, 49.8% (n = 2781) of whom were women and 30.4% (n = 1698) with NAFLD. There was a graded positive association between Adipo-IR and NAFLD, with sex (P = 0.01) and hyperlipidemia (P = 0.02) modifying this association. In the hyperlipidemic women, for one unit increase in log-Adipo-IR, the odds of having NAFLD increased by 385% after adjustment for potential confounders (OR = 4.85, 95%CI 3.54–6.73, P < 0.001). However, it turned out that the odds of having NAFLD increased by 131% (OR = 2.31, 95%CI 1.74–3.11, P < 0.001), 216% (OR = 3.16, 95%CI 2.56–3.93, P < 0.001), 181% (OR = 2.81, 95%CI 1.88–4.28, P < 0.001) in normolipidemic men, hyperlipidemic men, and normolipidemic women, respectively. Similarly, the ORs for the association between Adipo-IR and NAFLD in women with age ≥ 50 years were higher than ORs in women with age < 50 years. CONCLUSIONS: The positive correlation between Adipo-IR and NAFLD was stronger in hyperlipidemic women, compared with normolipidemic or hyperlipidemic men, or normolipidemic women. The association also strengthened for women over 50 years. Treatment strategies targeting Adipo-IR to alleviate NAFLD may be of value, especially in hyperlipidemic women after menopause.