To observe and evaluate the therapeutic effects of modified Minor Chest Bind Decoction on impaired glucose tolerance(IGT) in the pattern of dampness-heat accumulating spleen.Methods:60〖BP(〗（和中文摘要人数不一致）〖BP)〗patients of the abovementioned syndrome were randomized to treatment group (n=30) and control group (n=30), respectively treated with the decoction and metformin, besides life style intervention. Changes in syndromes, glucose, insulin releasing, insulin sensitivity, insulin resistance exponent were observed.Results:Treatment group was significantly different from control group in syndrome score, glucose score, insulin sensitivity, BMI, waist line, hip line.Conclusion:The decoction can significantly relieve the dampness-heat syndrome, lower glucose, enhance insulin sensitivity, reduce weight and waist line, while having little adverse reactions.