Diabetic retinopathy and cerebral hemodynamic impairment in type II diabetes

To assess whether a screening method based on transcranial Doppler (TCD) examination could detect signs of brain hemodynamic impairment in non-insulin-dependent diabetic patients with retinal microangiopathy of varying severity, asymptomatic for cerebrovascular diseases.

We studied 86 patients stratified according to the presence of proliferative diabetic retinopathy (PDR: 29 cases), background retinopathy (BDR: 32 cases) and no diabetic retinopathy (NDR: 25 patients). TCD was performed to record mean flow velocity and pulsatility index values in the middle cerebral (MCA), anterior cerebral (ACA) and ophthalmic arteries (OA), at rest. It was also employed to evaluate the cerebral vasodilatory response to a breath-holding test: the maximum percentage MCA flow velocity increase during the test was taken as an index of cerebrovascular reactivity. Fifty healthy subjects were studied to establish control values. Analysis of variance was used to test inter-group differences. The regression test was applied to define the relationship between TCD parameters and age and disease duration.

No significant differences were found between controls and the whole group of patients with respect to TCD parameters. However, subgroup analysis showed PDR patient had a significantly higher pulsatility index and lower cerebrovascular reactivity than BDR and NDR patients. This difference was not explained by the effect of age or disease duration, being greatest in patients under sixty.

These findings seem to confirm the hypothesis of a silent cerebral microangiopathy affecting diabetic patients, with concomitant signs of microangiopathic damage in other districts.