Abstract: Objective To understand the correlation between the diabetes and the complications and the constitution of traditional Chinese medicine (TCM) in Baoshan District in Shanghai, and to provide scientific evidence for carrying out the targeted prevention and intervention measures. Methods TCM body mass table was used to distinguish the TCM constitution of the diabetic patients and the control group. The relationship between TCM constitution and diabetes and its complications was analyzed by single factor and multiple factor logistic regression. Results There were less patients with yin-yang harmony constitution and yang deficiency constitution in the case group than in the control group, while more with qi deficiency constitution and phlegm-damp constitution than in the control group. Among a total of 879 cases of diabetic patients with 1 235 physical elements, the top four biased constitution elements were identified including constitution of qi deficiency (15.22%), yin deficiency (8.42%), yang deficiency (8.42%) and phlegm-damp (8.34%). The yin deficiency, qi deficiency and phlegm dampness constitution elements in the case group were significantly higher than in the control group.Among 875 cases in the control group with 1 129 physical elements, the top four biased constitution elements were yang deficiency (12.40%), qi deficiency (9.65%), yin deficiency (5.05%) and phlegm-damp (4.52%), which yin-yang harmony constitution and yang deficiency constitution elements were significantly higher than those of the case group. The incidence of complications of the diabetic patients with biased constitution was significantly higher than those with the yin-yang harmony constitution. Conclusion Phlegm dampness constitution, qi deficiency constitution and yin deficiency constitution are the main dangerous constitution of diabetes mellitus. The protective constitution of diabetes is yin-yang harmony constitution and yang deficiency constitution. The biased constitution elements are the risk factors of diabetes complications.