Abstract：Objective：To analyze the serum metabolomics and infrared thermography characteristics of diabetes mellitus patients of yin deficiency constitution，and to explore the correlation between them and serum inflammatory factors. Methods：A total of 43 diabetes mellitus patients of yin deficiency constitution were selected as “the group of diabetes mellitus patients of yin deficiency constitution”，and 43 healthy and neutral people were chosen as “the group of healthy and neutral constitution”. The ΔT values of infrared thermal image temperature and levels of serum tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in each functional area in the two groups were compared，and the correlation between ΔT values of infrared thermal image temperature in each functional area and inflammatory factors levels in the group of diabetes mellitus patients of yin deficiency constitution were analyzed by Pearson Test. The differential metabolites between the two groups were detected by liquid chromatogre-mass spectrometry (LC-MS)， and the key metabolic pathways were focused by principal component analysis (PCA)，partial least squares discriminant analysis (PLS-DA) and Metaboanalyst 5.0 software. Results：In the course of the study，three cases in the group of healthy and neutral constitution were excluded， and 40 cases completed the study eventually. In the group of diabetes mellitus patients of yin deficiency constitution， the ΔT value of conception vessel， governor vessel， palm， head and face， thoracic cavity， stomach cavity and kidney areas，and the levels of serum TNF-α and IL-6 were higher than those in the group of healthy and neutral constitution (P＜0.05)， and the ΔT value of hypoabdominal temperature was decreased (P＜0.05). There was no correlation between the ΔT value of infrared thermal image in each functional area and TNF-α levels in the group of diabetes mellitus patients of yin deficiency constitution (P＞0.05)，but there was a positive correlation between the ΔT value of infrared thermal image of conception vessel，palm，head and face and IL-6 levels (P＜0.05). Metabolomics studies have found that 15 different metabolites with obvious changes in the serum of diabetes mellitus patients of yin deficiency constitution， including palmitic acid， Lpiperidinic acid， deoxyribose， glucose， etc.， mainly involved in arachidonic acid metabolism， pentose phosphate pathway，D-glutamine and D-glutamic acid metabolism，galactose metabolism，and fatty acid bioanabolic pathway， in which the arachidonic acid metabolic pathway had the strongest correlation. Conclusion： Diabetes mellitus patients of yin deficiency constitution have the following characteristics： there is heat in the conception and governor vessels and "heat in the upper and cold in lower"， and the elevated level of serum IL-6 is related to the heat of conception vessel， palm， head and face. The pathogenesis of diabetes mellitus patients of yin deficiency constitution is related to five metabolic pathways：arachidonic acid pathway，galactose metabolism，fatty acid biosynthesis，pentose phosphate pathway，D-glutamine and D-glutamic acid metabolism，among which the AA-CYP-EETs metabolic axis in the arachidonic acid metabolic pathway may be the most important pathway.