Abstract： Objective To explore the correlation between HbA1c level and carotid plaque stability in type 2 diabetes mellitus(T2DM)patients.Methods From October 2018 to October 2020,100 T2DM patients who visited our hospital and underwent carotid artery ultrasound examination with a plaque thickness greater than 1.5 mm were included in this study.According to HbA1c levels,they were divided into HbA1c≤7%group(n=21),7%<HbA1c≤9%group(n=28),and HbA1c>9%group(n=51).Results The FPGs of the 7%<HbA1c≤9%and HbA1c>9%groups were higher than that of the HbA1c≤7%group(P<0.01).The plaque thickness gradually increased from group HbA1c≤7%,7%<HbA1c≤9%to HbAlc>9%groups(P<0.01),and the proportion of high-level enhancement in the overall,proximal,middle,and distal segments of the plaque increased in sequence(P<0.05 or P<0.01).Pearson correlation analysis showed that HbA1c,FPG,and 2 hPG were positively correlated with plaque thickness and length(P<0.05).Spearman correlation analysis showed that HbA1c was positively correlated with the smoothness of the plaque surface,the presence of extremely low echogenicity within the plaque,and the overall,proximal,central,and distal enhancement intensity of the plaque(P<0.05).Conclusion HbA1c can not only evaluate the blood glucose control of T2DM patients,but also has a certain correlation with the stability of carotid plaque,with a trend of poorer plaque stability as HbA1c increases.