The effects of blended Chinese traditional medicines applied for diabetes mellitus were studied on the pattern of action to the glucose tolerance curves in genetically diabetic KK-CAy mice. The glucose tolerance curves of KK-CAy mice (humping curve) were analyzed pharmacokinetically by the mathematical model (COmpartment-H model). The curves could be classified into several types of pattern through the analysis for the humping effect. Daisaikoto-Ka-Jio and Byakko-Ka-Ninjinto reduced the humping effect, whereas Hachimigan had a tendency to enhance it. On the combined effect of crude drugs prescribed in the blended medicines, the effect of Daisaikoto was lessened by subtracting Rehmanniae Rhizoma from Daisaikoto-Ka-Jio and Byakkoto (subtracted Ginseng Radix from Byakko-Ka-Ninjinto) had no inhibitory effect on the humping. Rehmanniae Rhizoma or Ginseng Radix along had the similar effect on decreasing the humping. the hypoglycemic component of Ginseng Radix (DPG3-2) decreased the humping effect in a dose-dependent manner. In conclusion, the effects of crude drugs and the active component of the crude drug supported those of the blended medicines on the humping effect by utilizing the pharmacolinetical analysis.