Abstract: Abstract Objective: To explor The effect of thyroid hormone on carotid arteries atherosclerosis in type 2 diabetic subjects with euthyroidism。Methods:248 T2DM patients who hospitalized in Tianjin Metabolic Disease Hospital between January to December,2010 were divided into four groups : 92 patients (control group) without stenosis,32 patients (mild stenosis group) with stenosis<30%,93 patients (moderate stenosis group) with 30%≤stenosis<70%,31 patients (severe stenosis group) with stenosis>70% by color Doppler ultrasound of carotid arteries . The serum thyroid hormone were analysed in subjects of groups.Results: There were significant differences in the values of serum triiodothyronine(FT3)、high-density lipoprotein（HDL-C）between severe stenosis group and other three groups（P<0.01 or P<0.05）；Spearman’s correlation analysis demonstrated that carotid arteries atherosclerosis was negatively correlated with FT3、HDL-C（P<0.01）and positively correlated with body mass index(BMI)、glycosylated HbA1c、course of disease、age、low-density lipoprotein（LDL-C）、trglyceride（TG）、total cholesterol(TC)、systolic blood pressure（SBP）、diastolic blood pressure.Logistic regression analysis showed that age、SBP、TG heightening are independent risk factors affected the severity of carotid arteries atherosclerosis，FT3、HDL-C heightening are independent protective factors affected the severity of carotid arteries atherosclerosis.Conclusion: FT3 within a normal level might be a protect factor for atherosclerosis in patients with T2DM.

Key words: Diabetes Mellitus, Type 2 DiabeticCarotid ArteriesAtherosclerosisThyroid Hormones