Ninety-four diabetic patients, asymptomatic for cerebrovascular disease, stratified according to the presence of proliferative retinopathy (PDR), background retinopathy (BDR) and no diabetic retinopathy (NDR) underwent transcranial Doppler evaluation. Impairment in neither blood flow velocity and pulsatility index recorded at the ophthalmic and intracranial arteries, nor in the vasodilatory response to a breath-holding test was found in patients, when compared to age-matched controls. The subgroup analysis showed that PDR patients had significantly higher pulsatility index and lower cerebrovascular reactivity values than BDR and NDR patients. Such a difference was not just due to age or disease duration, being greatest in patients under the sixties. In asymptomatic diabetic patients, PDR may be a predictor of early cerebral vessel involvement and should lead to investigate brain hemodynamics by screening procedures.