CD4 and type 2 diabetes mellitus: Recent studies have shown that the triglyceride–glucose (TyG) index—a surrogate marker of insulin resistance—is significantly elevated in PLWH with MASLD or T2DM and correlates negatively with the CD4/CD8 ratio and positively with the frequency of senescent CD8+ T cells, suggesting a direct association between insulin resistance and immunosenescence [32].