Glycerol kinase (GK) is an X-linked enzyme that catalyzes the phosphorylation of glycerol to sn-glycerol 3-phosphate, a critical metabolic intermediate. This reaction is essential for multiple biosynthetic and catabolic pathways, including glycerolipid and triglyceride synthesis, glycogenesis, glycolysis, and gluconeogenesis. GK is localized to both the cytosol and mitochondria, reflecting its role as a hub in cellular energy metabolism and lipid biosynthesis 1. Regulation of GK expression is responsive to metabolic signals; glucocorticoid treatment modulates GK mRNA expression in white and brown adipocytes, with cortisone inducing short-term upregulation (1.5-6 fold) but suppressing long-term expression 1. GK deficiency is a recognized monogenic disorder affecting glycerol metabolism. Beyond its canonical metabolic role, genetic activation of GK (proxied by GCK variants) shows causal associations with improved frailty-related outcomes, including enhanced grip strength, increased appendicular lean mass, faster walking pace, and longer telomere length, with some effects mediated through reduced C-reactive protein 2. These findings suggest GK activators may have therapeutic potential in managing age-related decline and metabolic disease, though clinical validation remains necessary.