To observe the effect of Guyuan Decoction on microcirculation disturbance of diabetic nephropathy.Methods:Sixty cases of type 2 diabetes were randomly divided into an observation group and a control group,who came to our department from July 1st,2015 to October 1st,2016,each group of 30 cases.The control group was treated with 1 tablet of enalapril per day and subcutaneous injection of insulin (Novolin R 30) 1 international units per kg; the observation group with extra use of Guyuan decoction.The duration was 6 weeks.Fasting blood glucose,urine protein excretion rate (UAER),blood urea nitrogen (BUN),creatinine (Scr),glomerular filtration rate (GFR),whole blood viscosity and platelet derived growth factor (PDGF) levels were tested before and after treatment.Results:After the treatment,fasting blood glucose and UAER level of the two groups were lower than those before treatment (P<0.05); comparing with the control group,after treatment,fasting blood glucose and UAER of the observation group decreased significantly (P<0.05).After treatment,BUN and Scr of the two groups of patients were decreased (P<0.05),GFR increased (P<0.05); the observation group was better (P<0.05).The decoction can reduce the whole blood viscosity and down regulate the expression level of PDGF,and the inhibition degree of the treatment group was higher than that of the control group (P<0.05).Conclusion:The Guyuan Decoction can improve microcirculation of diabetic patients with diabetic nephropathy,which may be one of the possible mechanisms of the therapeutic effect.