The diabetes is mainly treated by the oral administration of western medicines at present. Despite their rapid curative effect, there have been still many reports for the western medicines about their clinical adverse reactions, failure of effective prevention and treatment of complications and drug resistance. Hence, they are not suitable for long-term administration. Traditional Chinese medicines have a long history in treating diabetes mellitus (DM) , which is commonly known as Xiaokezheng in the theory of traditional Chinese medicines. In recent years, many scholars have taken extracts from traditional Chinese medicines or separated active constituents as the study objects in the expectation of developing new-type drugs for treating and preventing diabetes. Therefore, a large number of study reports have been emerged in this field. Due to their significant glucose-reducing effect and specific effect in treating complications of diabetes, traditional Chinese medicine Gardeniae Fructus and its iridoid component geniposide shall be given full attention. This paper summarized the advance in studies on the curative effect and action mechanism of Gardeniae Fructus and geniposide in preventing and treating diabetes.