1-Deoxyglucose (1,5-anhydroglucitol), a metabolite related to diabetes mellitus, was identified in human plasma by gas-liquid chromatography and by gas-liquid chromatography/mass spectrometry. Plasma polyols were accurately determined with a gas-liquid chromatograph equipped with an all-glass capillary column. The plasma content of 1-deoxyglucose in healthy persons varies with age. Although the precise physiological role of 1-deoxyglucose remains obscure, the method described here for determining the minor polyol components of plasma, as well as the findings of 1-deoxyglucose in the plasma of healthy subjects, may be useful for investigating the metabolic roles of 1-deoxyglucose.