3-O-(Carboxymethyl)-D-glucose (3-OMG-COOH) is a D-glucose derivative bearing a carboxymethyl ether at the 3-position. The carboxylic acid handle can be activated to NHS or other esters for conjugation, and the compound serves as a non-metabolized glucose mimic in transporter and tracer studies, including as a precursor for radiolabeled or fluorescent glucose-uptake probes.