Objective To observe and analyze the effect of HbA1c level on macular microcirculation in patients with type 2 diabetes mellitus (T2DM).Methods A cross-sectional study.One hundred and twenty-four T2DM patients (124 eyes) without diabetic retinopathy who diagnosed by the examination of fundus color photography in Lixiang Eye Hospital Of Soochow University during September to December 2017 were enrolled in this study.There were 59 males (59 eyes) and 65 females (65 eyes),with the mean age of 65.06±7.99 years old.All patients underwent BCVA,fundus color photography,and OCT angiography (OCTA).The history of diabetes,hypertension and dyslipidemia were recorded in detail.According to the HbA 1 c level,patients were divided into three groups,HbA1c ideal control group (group A,HbA1c ＜7％,67 eyes),HbA1c control group (group B,7％≤HbA1c≤9％,44 eyes),and HbA1c poor control group (group C,HbA1c＞9％,13 eyes),respectively.The 3 mm × 3 mm range of the macular area was scanned by OCTA instrument.The vascular density (VD) and skeleton density (SD) of nonsegmented retinal layer (NRL),superficial retinal layer (SRL) and deep retinal layer (DRL) in the macular area and foveal avascular zone (FAZ) area,non-circularity index,axial rate (AR) of SRL were measured.The correlation between HbA1c,BCVA and VD,SD ofNRL,SRL,DRL was analyzed statistically with Spearman correlation test.The correlation between systemic factors and the above indicators was analyzed statistically with linear regression analysis.Results The results of linear regression analysis showed that HbA1 c was significantly correlated with VD (t=-3.237,-3.156,-2.050) and SD (t=-0.3.45,-3.034,-2.248) of NRL,SRL and DRL (P＜0.05);but no correlation with FAZ,non-circularity index and AR (t=1.739,0.429,1.155;P＞0.05).The differences of VD (F=6.349,5.981,3.709),SD (F=7.275,6.085,1.904) and AR (F=0.027) of NRL,SRL and DRL in group A,B and C were statistically significant (P＜0.05);but the differences of FAZ (F=1.904),non-circularity index (F=0.280) was not statistically significant (P＞0.05).Significant differences (P＜0.05) of VD and SD of NRL were found between group A and B (t=1.987,2.201),group A and C (t=3.365,3.572),group B and C (t=2.010,2.076).Significant differences (P＜0.05) of VD and SD of SRL were found between group A and B (t=2.087,2.168),group A and C (t=3.197,3.194).There were significant differences (P＜ 0.05) in SD of DRL between group A and B (t=2.239),group A and C (t=-2.519).There was significant difference in VD of DRL between group A and C (t=2.363).The results of Spearman correlation analysis showed that HbA1c was negatively correlated with VD (r=-0.273,-0.255,-0.222;P=0.002,0.004,0.013) and SD (r=-0.275,-0.236,-0.254;P＜0.05) ofNRL,SRL,DRL;positively correlated with FAZ and BCVA (r=0.221,0.183;P＜0.05).BCVA was negatively correlated with VD (r=-0.210,-0.190,-0.245) and SD (r=-0.239,-0.207,-0.296) of NRL,SRL,and DRL (P＜0.05),but not correlated with FAZ (r=0.099,P＞0.05).Conclusion The decrease of macular perfusion and the morphological change of FAZ accompanied by HbA1c increased.