Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases worldwide. It is closely linked to various metabolic abnormalities. Serum insulin level, an important compensatory marker of insulin resistance, plays a key role in the development and progression of NAFLD. However, large-scale studies evaluating the association between serum insulin and NAFLD based on imaging-defined standards, such as the controlled attenuation parameter (CAP), are still limited. This study analyzed data from National Health and Nutrition Examination Survey 2017–2020. A total of 2791 eligible United States adults were included. Liver CAP values were measured using transient elastography, and fatty liver was defined as CAP ≥ 248 dB/m. Fasting serum insulin levels were also measured. Multivariable weighted logistic regression, restricted cubic spline analysis, and receiver operating characteristic curve analysis were used. These methods assessed the association between serum insulin levels and ultrasound-defined NAFLD, adjusting for demographic and metabolic confounders. After comprehensive adjustment for covariates, serum insulin levels treated as a continuous variable were significantly associated with increased odds of having NAFLD (odds ratio OR = 1.04; 95% confidence interval CI: 1.01–1.07; P = .014). Quartile-based analysis indicated that individuals in the highest insulin group (Q4) had significantly higher odds of having NAFLD compared with those in the lowest insulin group (Q1; OR = 3.61; 95% CI 1.84–7.08; P = .006). Restricted cubic spline analysis revealed a significant positive nonlinear relationship between serum insulin levels and NAFLD ( P for non-linearity < .05). Receiver operating characteristic curve analysis demonstrated that serum insulin had good discriminative ability for predicting NAFLD, with an area under the curve of 0.774 (95% CI: 0.757–0.792). Multiple sensitivity and subgroup analyses further confirmed the robustness of the results. Overall, these findings suggest that serum insulin levels are significantly and positively associated with ultrasound-defined NAFLD. Serum insulin also shows good independent predictive ability. It may serve as an important metabolic biomarker for early screening and risk assessment of fatty liver.
Li et al. (Fri,) studied this question.