The aim of this study was to determine the role of colour Doppler imaging in the retrobulbar vascular circulation in diabetic retinopathy (DR). Maximum (V(max)), end-diastolic (V(min)) and average (V(mean)) velocities of blood flows and pulsatility index and resistivity index (RI) in central retinal artery (CRA), short branches of posterior ciliary artery (PCA) and ophthalmic artery of the 65 diabetic and 22 control eyes were measured. The CRA V(max) level in the control group was significantly higher than in DR groups. The CRA V(mean) level was also significantly higher in the control group than in the mild nonproliferative diabetic retinopathy (NPDR) and the moderate NPDR groups. The CRA RI value was significantly higher in the control group than in the nonretinopathy group. The CRA V(min) and the ophthalmic artery RI values were found significantly higher in the nonretinopathy group than in the moderate NPDR group. There were significant decreases in the some CRA and PCA values as glycated haemoglobin (HbA1c) levels increase in diabetic group. There was a positive correlation between the duration of diabetes and HbA1c levels. This study showed the presence of some dynamic circulatory alterations in the nonretinopathy group with diabetes and DR groups. It was also shown that there is a negative correlation between HbA1c and some orbital vascular velocities.