To assess the relationship of retinal vessel diameter and diabetic retinopathy (DR) in a subgroup of participants recruited through the Darwin Region Urban Indigenous Diabetes study.Participants were examined as part of the Darwin Region Urban Indigenous Diabetes study. All participants with gradable fundus photographs were included in the current analysis. Assessment of retinal vascular diameter, including arteriolar diameter (central retinal arteriolar equivalent) and venular diameter (central retinal venular equivalent), was undertaken using a semi-automated retinal vascular imaging program. DR was graded according to the modified Early Treatment DR Study scale.A total of 110 participants, 25 men and 85 women, with a mean age of 50.8 years were included in the analysis. The odds ratio for having DR for each standard deviation increase in central retinal venular equivalent was as high as 1.62 (95% confidence intervals 0.94, 2.80); however, this did not reach statistical significance (P = 0.08). Moreover, individuals with severe non-proliferative DR and proliferative DR were found to have narrower arteriolar diameters compared with those with no DR, but this was not statistically significant (-8.1 microm, 95% confidence intervals, -39.3 microm, 23.1 microm; P = 0.612).Our data indicate a trend for narrower arteriole diameter and wider venular diameter with DR in this high-risk ethnic group, which concurs with overall trends seen in non-indigenous populations.