Objective :To explore the correlation between serum gamma-glutamyl transpeptidase (GGT ) level and carotid atheromatous plaque in patients with type 2 diabetes mellitus (T2DM ) accompanied by nonalcoholic fatty liver disease (NAFLD) . Methods :The clinical data of 230 patients with T2DM admitted during January 2010 and June 2015 were retrospectively analyzed .Patients were divided into three groups :simple T2DM with normal GGT level(GGT < 50 U /L)group (Group A ,n= 100) ,T2DM accompanied by NAFLD with normal GGT level(GGT < 50 U /L)Group (Group B ,n= 100) ,and T2DM accompanied by NAFLD with abnormal GGT level (GGT ≥ 50 U /L) Group (Group C ,n= 30) .Each patient's data such as age ,sex ,course of disease ,current smoking ,carotid plaque ,systolic blood pressure (SBP) ,body mass index (BMI) ,waist circumference (WC) ,fasting plasma glucose (FPG) ,two hours postprandial glucose (2 h PG) ,glycosylated hemoglobin A1c (HbA1c) ,total cholesterol (TC) ,triglyceride (TG) ,low density lipoprotein cholesterol (LDL-C) ,high density lipoprotein cholesterol (HDL-C ) ,gamma-glutamyl transpeptidase (GGT ) , alanine aminotransferase (ALT ) , fasting serum c-peptide (FCP) ,and high-sensitivity c-reactive protein (hsCRP) ,were collected and evaluated .Results :The incidence rate of carotid plaque in Group C(83 .3% ,25/30)was significantly higher than that in Group B(64% ,64/100)and Group A (60% ,60/100) , however ,there was no significant difference . There were statistically significant differences regarding BMI , WC , FPG , HbA1c ,LDL-C ,hsCRP between Group A and Group B and Group C (P< 0 .017) ,however ,there was significant difference regarding HDL-C between Group A and Group B (P < 0 .017) ,there was significant difference regarding SBP ,2 h PG ,TG between Group A and Group C (P< 0 .017) .The BMI ,FPG ,2 h PG ,HbA1c ,GGT ,ALT ,TG in Group B was significantly higher than those in Group C (P < 0 .017) .There was no statistically significant difference regarding TC and FCP among 3 groups .Result of multiple logistic regression analysis showed that group(Group B vs Group A ,Group C vs Group A ) ,age , course of disease were the independent risk factors of incidence of carotid atheromatous plaque ,and their odds ratio(OR) were (7 .533 ,40 .418) ,1 .194 ,and 1 .135 .Conclusions :The abnormal level of GGT in patients with T2DM accompanied by NAFLD is correlated with the occurrence and development of carotid atheromatous plaque .