Aim To study the association between serum adiponectin and insulin resistance in the type 2 diabetes mellitus patients with obesity,and investigate the role of serum adiponectin in the type 2 diabetes mellitus patients with obesity who had insulin resistance. Methods 30 T2DM patients with obesity,25 T2DM patients,and 25 controls which included 13 with obesity were selected. Their body mass index (BMI),waistline,fasting plasma glucose (FPG),hemoglobin a1c( HbA1c),fasting insulin (FINS) ,and the serum levels of total cholesterol,triglyceride and adioponectin were measured. Then the HOMA-IR and ISI were calculated. At last,the relationships between serum adioponectin and insulin resistance were analyzed. Results ⑴The BMI,HbA1c,FPG,HOMA-IR,FINS were significantly higher in diabetic obese group than control obese group,serum adiponectin and ISI was significantly lower in diabetic obese group(P<0.05). (2)The triglyeride,HbA1c,FPG,HOMA-IR,FINS were higher in diabetic group without obesity than control group without obesity,serum adiponectin and ISI was lower in diabetic group without obesity(P<0.05). (3)The triglyeride,cholesterol,HbA1c,FPG,HOMA-IR,FINS,waistline were higher in diabetic obese group than diabetic group without obesity,serum adiponectin and ISI was lower in diabetic obese group(P<0.05). Conclusion The serum adiponectin level were correlated with insulin resistance in obesity with type 2 diabetes mellitus patients. Lower adiponectin leads to insulin resistance.The level of adiponectin can serve as an indicator in detecting insulin resistance in type 2 diabetes mellitus patients with obesity.