Objective To study the effect and mechanism of Chinese medicine Tangnaikang on type 2 diabetes mellitus. Methods Totally 44 wistar rats were randomly divided into Chinese medicine group（ n = 18）

blank group（ n = 20）

and western medicine group（ n = 6）. Perfused Chinese medicine group with Tangnaikang to prepare Chinese medicine serum; Perfused western medicine group with Pioglitazone to prepare western medicine serum;Perfused blank group with distilled water to prepare blank serum. Insulin resistance model was made with 3T3-L1 adipocyte

then were divided into model group

Pioglitazone group

Tangnaikang group of high

middle and low dosages group

and normal adipocyte was taken as blank group. Tangnaikang high dosage group was given nutrient solution containing Chinese medicine serum. Tangnaikang middle dosage group was given confected nutrient solution containing one part blank serum and two parts Chinese medicine serum. Low dosage group was given nutrient solution containing two parts blank serum and one part Chinese medicine serum. Pioglitazone group was given nutrient solution containing western medicine serum. Blank and model group were given basic nutrient solution. After cultivating for72 h

determined content of TNF-α with ELISA

observed the expression of TNF-α protein using the immunofluorescence method

and determined the level of TNF-α mRNA using RT-PCR method. Results TNF-α protein level of adipocyte in model group increased remarkably compared with normal group（ P < 0. 01）; TNF-α protein level of all medication groups was lower than that of the model group remarkably（ P < 0. 01）

and that of Tangnaikang high and middle dosage group was lower than that of Pioglitazone group remarkably（ P < 0. 01）. There were abundant TNF-αpositive reaction particle in cells of model group. TNF-α positive reaction particles of Tangnaikang middle and high dosage group and Pioglitazone group decreased remarkably compared with model group. Compared with the model group

expression of TNF-α mRNA of Tangnaikang high and middle dosage group and Pioglitazone group decreased remarkably

and that of Tangnaikang middle dosage group was the least. Conclusion Tangnaikang can effectively improve insulin resistance of mature 3T3-L1 adipocyte

remarkably decrease expression level of TNF-α protein and mRNA in insulin resistance 3T3-L1 adipocyte. This might be one of the mechanism of Tangnaikang in treatment of type 2 diabetes mellitus.