Objective:The purpose of this study was to explore the therapeutic effect of modified Xiaoke prescription on patients with Yin deficiency and heat excessive type 2 diabetes mellitus (T2DM), and its influence on TCM syndrome scores, pancreatic islet function and oxidative stress.Methods:Randomized controlled trial. Eighty patients with Yin deficiency and heat excessive T2DM treated in the hospital between January and July 2021 were selected, and divided into observation group (41 cases) and control group (39 cases) by random number table method. Patients in the control group were treated with conventional western medicine, and patients in the observation group were treated with modified Xiaoke Prescription on the basis of the control group. Both groups were treated for 1 month. TCM syndrome scores were performed before and after treatment. Fasting plasma glucose (FPG) and 2 hPG were measured by glucose oxidase method. Serum HbA1c, malondialdehyde (MDA), 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels and SOD activity were measured by ELISA. The levels of low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) and total cholesterol (TC) were detected by colorimetry.Results:The total effective rate of the observation group was 92.68% (38/41), and that of the control group was 76.92% (30/39). The difference between the two groups was statistically significant ( χ2=3.89, P=0.048). After treatment, the scores of tiredness and fatigue, thirst and appetite, overeating and hunger, redness of tongue and lack of saliva and total scores in the observation group were significantly lower than those in the control group ( t=4.46, 16.89, 13.37, 8.58, 8.38, P<0.01). After treatment, the levels of serum FPG [(7.31±0.90) mmol/L vs. (8.72±1.50) mmol/L, t=5.13], 2 hPG [(9.64±2.05) mmol/L vs. (12.85±1.20) mmol/L, t=8.49], HbA1c [(7.64±0.58)% vs. (8.11±1.35)%, t=2.04] in the observation group were significantly lower than those in the control group ( P<0.05); MDA [(3.96±1.00) mmol/L vs. (5.04±0.73) mmol/L, t=5.49], 8-OHdG [(203.41±30.70) ng/L vs. (234.50±59.00) ng/L, t=2.98] levels were significantly lower than those in the control group ( P<0.05); The activity of serum SOD [(48.64±5.05) mU/L vs. (41.75±3.58) mU/L, t=7.01] was significantly higher than that of the control group ( P<0.01); The serum LDL-C [(2.01±0.11) mmol/L vs. (2.56±0.25) mmol/L, t=12.84], TC [(4.75±0.20) mmol/L vs. (5.12±0.07) mmol/L, t=10.93] levels were significantly lower than those in the control group ( P<0.01); The serum HDL-C [(1.62±0.18) mmol/L vs. (1.24±0.42) mmol/L, t=5.31] level was significantly higher than that of the control group ( P<0.01). Conclusion:The modified Xiaoke Prescription can improve clinical symptoms, curative effect and pancreatic function, and relieve oxidative stress on the patients with T2DM.