AIM: To quantify changes in peripapillary vessel density in patients with type 2 diabetic mellitus(DM)without clinical features of diabetic retinopathy(DR)by OCT angiography(OCTA). METHODS:A retrospective clinical study. From January to December 2019, 38 type 2 DM patients without DR(38 eyes, NDR group)and 30 normal subjects(30 eyes, control group)in Eye Hospital of Wenzhou Medical University at Hangzhou were included in the study. The optic nerve head was scanned by OCTA with HD 4.5mm×4.5mm imaging scanning mode for all subjects.The software automatically divides the peripapillary region into 8 sectors, designated as nasal superior(NS), nasal inferior(NI), inferior nasal(IN), inferior tempo(IT), tempo inferior(TI), tempo superior(TS), superior tempo(ST)and superior nasal(SN). Radial peripapillary capillaries vessel density(ppVD)and peripapillary retinal nerve fiber layer(pRNFL)thickness of entire peripapillary area and each sector were measured. The discrepancy of ppVD and pRNFL thickness between the two groups was also analyzed. Pearson correlation analysis was used to analyze the correlation between ppVD and pRNFL in each quadrant of NDR group. RESULTS:The mean ppVD value and NS,NI,IN,IT,TI,TS,ST and SN sector values were all significantly lower in NDR group compared to normal controls(all P<0.05). The mean and each sector pRNFL thickness was reduced in NDR group compared with the control group, but the difference was not statistically significant(all P>0.05). Pearson correlation analysis showed that the significant positive correlation was found between ppVD and pRNFL thickness in TI, TS, SN, NS and NI sector(r=0.578, 0.427, 0.577, 0.397, 0.317; all P<0.05). CONCLUSION: Peripapillary vessel density has decreased in eyes of patients with type 2 DM before clinically detectable retinopathy and OCTA is helpful for early monitoring.