Muscle loss and GLP-1R agonists use.

Skeletal muscle wasting is a major yet often overlooked determinant of adverse outcomes in diabetes mellitus and obesity. Loss of muscle mass and strength not only impairs mobility and quality of life, but also worsens insulin resistance, accelerates cardiometabolic decline and increases mortality risk. The convergence of chronic inflammation, mitochondrial dysfunction and altered protein metabolism makes individuals with metabolic diseases particularly vulnerable to sarcopenia. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) have transformed the therapeutic landscape of type 2 diabetes (T2D) and obesity by offering substantial weight loss and cardiometabolic protection. However, clinical trials and real-world evidence consistently show that weight reduction with GLP-1RAs is accompanied by decrease in lean body mass, raising concern in patients already predisposed to muscle wasting and underscoring the need for integrated management strategies. By including all English-language studies on muscle mass loss during GLP-1RA therapy in T2D and obesity from major scientific databases and clinical trial registries, this narrative review synthesizes the current knowledge on the epidemiology and mechanisms of muscle loss in diabetes and obesity, with a focus on the impact of GLP-1RAs therapy. It further examines preventive and therapeutic strategies to preserve muscle health during pharmacological weight loss, with the ultimate aim of providing clinicians and researchers with practical insights and future directions to maximize the benefits of GLP-1RAs while mitigating the risk of sarcopenia.