Objective To observe clinical effects of modified Guizhi Tang（ 桂枝汤） to treat diabetic cardiac autonomic neuropathy. Methods Totally 161 patients were randomly divided into test group（ 81 cases） and control group（ 80 cases）. On the basis of the conventional treatment

the test group was given modified Guizhi Tang

1 dose daily. On the basis of the conventional treatment

the control group took orally mecobalamin

0. 5 mg each time

3 times a day. Both groups were treated for 8 weeks. Compared scores of Chinese medicine syndrome

index of heart rate variability [standard deviation of R-R interval（ SDNN）

root-mean-square of difference value between adjacent R-R interval in the whole course（ r MSSD）

recording percentage between the numbers that difference value greater than 50 ms between adjacent R-R interval and the total numbers of R-R interval in the whole course（ PNN 50）

low frequency（ LF）

high frequency（ HF） and LF/HF]before and after treatment

and levels of serum inflammatory cytokines including interleukin 6（ IL- 6）

tumor necrosis factor α（ TNF-α） and transforming growth factor β1（ TGF-β1） in the two groups were tested to evaluate the curative effects of Chinese medicine syndrome after treatment. Results In the test group

total effective rate about curative effects for Chinese medical syndromes was100% but that for the control group was 83. 75%. The test group was better than the control group（ P < 0. 05）. After treatment

levels of SDNN

r MSSD

PNN 50

LF

HF and TGF-β1 increased significantly in the treatment group and IL-6

TNF-α

LF / HF

the score of single symptom and the total score decreased significantly（ P < 0. 05 or P <0. 01）. In the control group

SDNN

r MSSD

LF

HF increased obviously after treatment but IL-6

scores of palpitate

choking sensation in chest and fatigue and the total score decreased significantly（ P < 0. 05）. In the test group

SDNN

r MSSD

PNN 50

LF

HF

TGF-β1 were significantly higher than those in the control group after treatment（ P < 0. 05 or P < 0. 01） but IL-6

TNF-α

LF/HF

score of the single symptom and the total score were significantly lower than those in the control group（ P < 0. 01）. Conclusion Modified Guizhi Tang may significantly improve clinical symptoms of patients with diabetic cardiac autonomic neuropathy

improve inflammatory condition and correct imbalance of cardiac autonomic nerve.