Nonlinear relationship between the CHG index and MASLD in type 2 diabetes mellitus: mediating role of immunoinflammatory markers

To investigate the relationship between cholesterol, high-density lipoprotein, and glucose (CHG) index and metabolic dysfunction-associated steatotic liver disease (MASLD) in patients with type 2 diabetes mellitus (T2DM). 1,789 patients with T2DM aged ≥50 years were divided into MASLD (age: 62.56 ± 7.59) and non-MASLD groups (age: 62.78 ± 7.79). Adjusted regression models, threshold analysis, mediation analysis, and receiver operating characteristic (ROC) curves were used. Based on CHG index levels and various immunoinflammatory markers, patients with T2DM were divided into different groups, and the prevalence of MASLD was compared. The CHG index, neutrophil-to-albumin ratio (NAR), neutrophil-to-lymphocyte ratio (NLR,) systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), and aggregate inflammation systemic index (AISI) were higher in the MASLD group than in the non-MASLD group (p < 0.05). Multiple logistic regression analysis showed that the CHG index, NAR, NLR, SII, SIRI, and AISI were positively correlated with MASLD risk (all p < 0.05). Threshold analysis showed that when the CHG index was <5.474, it was positively associated with MASLD risk (p < 0.05). MASLD prevalence increased with increasing levels of inflammatory markers and the CHG index (p < 0.05). Mediation analysis of NAR, NLR, and SII between the CHG index and MASLD showed that the total effect estimates were 0.0159, 0.0153, and 0.0157, respectively; the direct effect estimates were 0.0107, 0.0134, and 0.0120; and the mediation effect estimates were 0.0053, 0.0019 and 0.0037, with the mediated proportions accounting for 27.25%, 11.47%, and 27.25% of the total effect, respectively. ROC curve analysis showed that the CHG index combined with SIRI had improved diagnostic performance for MASLD, with an area under the curve of 0.71. The CHG index was positively associated with MASLD risk in patients with T2DM aged ≥50 years. NAR, NLR, and SII partially mediated this association, highlighting their potential application in MASLD diagnosis.