Objective To observe the effect of Wendan Decoction（ WDD） on blood glucose of rats with impaired glucose tolerance（ IGT） induced by high fat diet and to discuss the possible mechanism. Methods The rats were fed for 20 weeks with high fat diet to establish IGT rat models. Then 12 successful models were randomly divided into model control group and WDD group

with 6 rats in each. Another 6 rats with normal blood glucose levels were assigned in normal control group. The normal control group and model control group were given distilled water 10 ml /（ kg·d） by gavage

while WDD group was given WDD solution 1. 88 g /（ kg·d）

all for 2 weeks. The body weight

fasting blood glucose

postprandial 2 h blood glucose

perirenal and epididymal fat weight

triglyceride（ TG）and total cholesterol（ TC） were tested

and the proportion of fat and weight

as well as Lee’s index were calculated for each group. Results Compared with those of the normal control group

the weight

postprandial 2 h blood glucose

perirenal and epididymal fat weight

the proportion of fat and weight

Lee’ s index

serum TG and TC in the model control group were significantly lower（ P < 0. 05 or P < 0. 01）. Compared with those in the model control group

the postprandial 2 h blood glucose

perirenal and epididymal fat weight

the proportion of fat and weight

Lee’s index

serum TG and TC in the WDD group were significantly lower（ P < 0. 05 or P < 0. 01）. Conclusion WDD could improve the diseased conditions of IGT rats

which may be related to reducing the postprandial 2 h blood glucose

fat accumulation and blood lipid levels.