Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive motor neuron loss and profound systemic metabolic dysfunction, including hypermetabolism, weight loss, insulin resistance, and altered glucose and lipid homeostasis. Increasing recognition of these metabolic abnormalities has driven interest in repurposing antidiabetic therapies, particularly glucagon-like peptide-1 (GLP-1) and GLP-1 receptor agonists (GLP-1RAs), for ALS. Beyond their established metabolic actions, GLP-1RAs exert pleiotropic effects relevant to neurodegeneration, including modulation of neuroinflammation, mitochondrial function, oxidative stress, excitotoxicity, and cell-survival signaling, with selected agents demonstrating central nervous system penetration. This narrative review summarizes current knowledge on metabolic impairment in ALS and critically evaluates the mechanistic rationale, preclinical evidence, and emerging clinical data supporting or opposing the use of GLP-1-based therapies in this disease. Preclinical studies suggest that GLP-1 signaling can provide neuroprotective and neurotrophic effects in ALS models, although findings are heterogeneous and highly dependent on compound selection, delivery strategy, and experimental design. In contrast, available clinical evidence is limited and does not demonstrate therapeutic benefit in ALS, while raising important safety concerns, particularly related to weight loss, lean mass reduction, and altered glucose regulation, factors associated with a worse prognosis in ALS. Collectively, current data indicate that although GLP-1-based therapies may have compelling biological plausibility and beneficial effects in other neurodegenerative disorders (NDGs), their role in ALS remains uncertain and potentially harmful. Well-designed, ALS-specific clinical studies are required to clarify safety, efficacy, and patient selection before GLP-1RAs can be considered for therapeutic use in this vulnerable population.
