Gas chromatographic-mass spectrometric determination of 13C-glucose level for evaluating the effect of alpha-glucosidase inhibitor acarbose on the digestion of [U-13C] starch in rat.

The effect of acarbose on the digestion of starch was examined by a stable isotope tracer technique. [U-13C]-Starch was administered orally to rats with or without acarbose. After the addition of [2H3]-D-glucose as the internal standard, the plasma samples were treated successively for defatting, deproteinizing and desalting. Glucose was converted to sorbitol by reduction with sodium borohydride. The cyclic butylboronate of sorbitol was injected into a gas chromatograph-mass spectrometer, and the concentration of labeled glucose was measured by selected monitoring of the quasi-molecular ion. The plasma concentration of labeled glucose was decreased significantly by the addition of acarbose. The effect of acarbose on the digestion of starch was clearly confirmed using [U-13C]starch.