Cuproptosis is a recently identified form of regulated cell death driven by the direct binding of Cu⁺ to the lipoyl moiety of mitochondrial tricarboxylic acid (TCA) cycle enzymes, leading to dihydrolipoamide S-acetyltransferase (DLAT) oligomerisation, iron-sulfur cluster (Fe-S) protein depletion, and proteotoxic stress, and is uniquely dependent on mitochondrial respiration. This review critically synthesises current evidence on the role of cuproptosis in type 2 diabetes mellitus (T2DM), metabolic dysfunction-associated steatotic liver disease (MASLD), and obesity. In T2DM, three causally validated pathways of copper transporter dysregulation converge on ferredoxin 1 (FDX1)-dependent DLAT oligomerisation, with substantial FDX1 reduction in diabetic skeletal muscle providing quantitative evidence of cuproptotic commitment; however, β-cell-specific knockout studies remain critically absent. In MASLD, indirect reactive oxygen species (ROS)-mediated insulin resistance is favoured over direct copper-receptor interactions. We propose the metabolic threshold hypothesis, positing that cuproptosis represents failed adaptation to chronic lipid overload, triggered when copper influx exceeds the combined buffering capacity of ATPase copper transporting beta (ATP7B)-mediated efflux, metallothionein sequestration, and glutathione (GSH) chelation. The serum Cu/Zn ratio cannot distinguish cuproptosis from ferroptosis; precise identification requires combined detection of FDX1, DLAT, lipoic acid synthase (LIAS), and lipoyltransferase 1 (LIPT1) with mitochondrial copper content, with immunohistochemistry (IHC) for DLAT oligomerisation as the most clinically accessible surrogate marker. Copper chelators including tetrathiomolybdate and merestinib are primary agents for metabolic tissue preservation, whereas ionophores such as elesclomol are restricted to oncology, with lipid nanoparticle-based delivery platforms essential to overcome the blood-brain barrier challenge, as underscored by the neurological worsening documented in D-penicillamine-treated Wilson disease patients. The interplay between cuproptosis and ferroptosis, sharing GSH depletion but diverging at lipoylated protein aggregation versus glutathione peroxidase 4 (GPX4)-dependent lipid peroxidation, suggests dual-pathway inhibition may be necessary. Future priorities include validation of the metabolic threshold hypothesis, β-cell-specific knockout studies, standardised DLAT oligomerisation diagnostics, tissue-targeted copper modulator delivery, and integration of cuproptosis biomarkers with multi-omics and artificial intelligence for clinically stratified precision medicine.
