An isotope dilution mass spectrometric method has been developed for kinetic studies of D-glucose in humans, using 6,6-dideuteroglucose as the internal standard. Glucose in plasma samples was purified by anion and cation exchange column chromatography after deproteinization and derivatized to α-D-glucofuranose cyclic 1,2:3, 5-bis (butylboronate)-6-acetate. The analysis was done by isothermic injection into a gas chromatograph electron impact quadrupole mass spectrometer monitoring selected ions. The dideuteroglucose enrichment that was used for this study was in the range of 0.4-2%. Coefficients of variation of isotope enrichment measured i n this range were less than 3% within-day and less than 5% between-day.