| OBJECTIVE: To observe the characteristics of changes in the appearance and signs of TCM and laboratory indexes related to syndromes in diabetic mellitus (DM) rats, analyze the evolution of syndromes in diabetic rats, and provide ideas for the establishment of diabetes syndrome models. METHODS: Diabetic rat model was established by intraperitoneal injection of 65 mg·kg-1 streptozotocin, and the fasting blood glucose ≥16.7 mmol·L-1 at 72 h (0 week) was used as the model standard. At 0 week(0 w), 3 w, 4 w, 5 w, and 10 w of the model, observe the appearance signs of the rats: body weight, hair color and hair state (soft, withered and yellow, dull, erected, depilated), mental state (normal, debilitating) , behavioral status (normal, less movement, squinting eyes, arched back), food intake, water consumption, urine and stool condition, red degree C value of the tongue, claw and nose in specific areas and ability to move independently; and the laboratory indexes at the corresponding time points were determined: the plasma glucose, FT3, FT4, cAMP, cGMP, and cortisol content of rats, and calculated cAMP/cGMP.RESULTS: Compared with the control group, DM rats significantly increased their food intake, water intake and urine output during model 0w, and continued to 10w (P<0.01). Body weight, nasal color C, autonomic activity, plasma FT3 and The concentration of FT4 decreased significantly and lasted to 10w (P<0.01); the plasma cAMP/cGMP increased significantly during the 3w of the model and continued to 10w (P<0.05), and the dry stool was black, the hair was yellow and dull, and the hair was standing ; Plasma cortisol concentration increased significantly at 4w after modeling, and lasted to 10w (P<0.01); DM rats at 5w after modeling showed symptoms of dryness and thinness of stool and yellowness and malaise; C degree value of tongue redness at 10w It was significantly lower than the control group (P<0.01).CONCLUSION: The model of diabetic rats established by intraperitoneal injection of streptozotocin at a dose of 65 mg/kg is stable within 10 weeks. In the early stage, the internal heat is predominant, and STZ can damage the body's yangqi, so it has mild yang deficiency. and has been throughout. Qi-yin deficiency appears in 3-5 weeks, and yin-yang deficiency in 10 weeks.