Nicotinamide mononucleotide (NMN) enhances NAD+ biosynthesis, which activates sirtuins (SIRTs) and promotes insulin signaling pathways, including the phosphorylation of AKT and mechanistic target of rapamycin (mTOR), thereby improving muscle insulin sensitivity and metabolic function. NMN also regulates mitochondrial dynamics and quality control through mitophagy, influenced by the PINK1-PRKN pathway, and mitigates age-associated physiological decline by restoring NAD+ levels and modulating the CX43-PARP1 axis in vascular aging. While the precise mechanisms of NMN's action on various signaling pathways are still being elucidated, its role in enhancing NAD+ availability is well established.