Abstract： Chinese medicine treatment has the advantages of good curative effects and mild adverse reactions in the treatment of type 2 diabetes mellitus (T2DM). Based on the etiology and pathogenesis of Chinese medicine，combined with modern etiology and pathology，this paper takes the mutual reference of Chinese and western medicine， reveals the pathogenesis in the early and late stages of T2DM， and explains the correlation between Chinese medicine theory and clinical manifestations of modern medicine. From the perspective of yin and yang，this paper points out that yin-yang disharmony is the fundamental cause of the disease，and explores the relationship between "illness arising from overuse" and the onset of T2DM，thus providing a theoretical basis for the staging treatment of T2DM.