Abstract: Objective　To study the differences and causes of oral glucose tolerance test (OGTT) by hexokinase(HK) method and glucose oxidase(GOD) method.   Methods　The patients were classified into A，B and C groups randomly. Orally taking 75 g glucose dissolved in 300 mL warm water was as A group，taking 150 mL 0.5 g/mL glucose injection was as B group，and taking 75 g glucose dissolved in 300 mL warm water placed overnight was as C group. The blood glucose levels at fasting，30，60，120 and 180 min after taking were determined by the 2 methods，and the differences of the results between the 2 methods were analyzed comparatively.   Results　There was no statistical difference of blood glucose levels between HK and GOD methods at each determination point in B and C groups (P>0.05). The blood glucose levels in A group between the 2 methods had no statistical significance (P>0.05). The blood glucose levels in A group at 30，60，120 and 180 min had obvious differences (P<0.05).   Conclusions　As GOD method is highly specific to beta-D glucose，the phenomenon of a relatively low OGTT curve may occur from the influence of alpha glucose.

Key words: Glucose, Oral glucose tolerance test, Diabetes mellitus, Hexokinase method, Glucose oxidase method