Diabetes duration modifies the association between AIP and MAFLD in type 2 diabetes

Abstract

Metabolic dysfunction-associated fatty liver disease (MAFLD) is highly prevalent in patients with type 2 diabetes mellitus (T2DM). Although several insulin resistance (IR)-related indices have been proposed as surrogate markers, their comparative performance and the influence of diabetes duration remain unclear. We compared the associations of eight IR-related indices with MAFLD and evaluated the modifying effect of diabetes duration. This retrospective cross-sectional study included 5,996 patients with T2DM, of whom 3,087 had MAFLD. Logistic regression was used to evaluate the associations of eight IR-related indices (TyG, TyG-BMI, METS-IR, CHG, CTI, HOMA-IR, SHR, and AIP) with prevalent MAFLD. To facilitate comparison across indices measured on different scales, odds ratios (ORs) were additionally estimated per 1-standard deviation (SD) increase. Receiver operating characteristic (ROC) curve analysis was used to assess discriminative performance. LASSO regression was used for covariate selection, followed by multivariable logistic regression, restricted cubic spline (RCS) analysis, and interaction analysis. Internal validation of the multivariable model was performed using 1,000 bootstrap resamples. All eight IR-related indices were significantly associated with prevalent MAFLD. After standardization, AIP showed the largest association estimate per 1-SD increase (OR = 2.137, 95% CI: 2.007–2.275). AIP also showed the highest, although moderate, discriminative performance among the eight indices (AUC = 0.692). After LASSO-based covariate selection and multivariable adjustment, AIP remained independently associated with prevalent MAFLD (OR = 4.968, 95% CI: 4.100–6.035). Adjusted RCS analysis indicated a nonlinear association between AIP and prevalent MAFLD (P for overall < 0.001; P for nonlinearity = 0.040). The revised multivariable model had an apparent AUC of 0.758 (95% CI: 0.746–0.771), with an optimism-corrected AUC of 0.756 after bootstrap internal validation. Significant interactions were observed between AIP and diabetes duration when duration was modeled continuously (P for interaction = 0.031) and categorically (<5 vs. ≥5 years; P for interaction = 0.001). Among the eight IR-related indices evaluated, AIP showed the largest standardized association with prevalent MAFLD and the highest discriminative performance in patients with T2DM. The association between AIP and MAFLD may vary according to diabetes duration.