Cerebral and Ophthalmic Artery Hemodynamic Responses in Diabetes Mellitus

OBJECTIVE To address whether hemodynamic responses in the cerebral arteries and OAs may be altered in patients with diabetic retinopathy. We used TCD to evaluate the effects of changes in BP, posture, and exercise on MCA and OA blood flow velocities.

RESEARCH DESIGN AND METHODS We evaluated 13 patients with BDR, 19 with PDR, and 11 control subjects. Each was tested while supine, breathing 100% oxygen, sitting, and during exercise.

RESULTS Control subjects exhibited linear increases in velocity in the MCA and OA with increases in BP. Those with BDR had higher baseline sBP than control subjects. The MCA velocity response to BP in the BDR group was parallel to, but differed significantly from, the response in control subjects in compensation for the level of BP (ANCOVA F_1,53 = 10.1, P = 0.003). The OA velocity response to BP was indistinguishable between the control subjects and the group with BDR. The group with PDR had more elevated BP than control subjects, and those with BDR had more advanced autonomic neuropathy. The PDR group had heterogenous velocity responses in the MCA and OA with respect to BP. None of the control subjects and 3 of 13 of the BDR group had abnormal autoregulatory velocity responses in the MCA or OA to 100% oxygen breathing, whereas 12 of 19 PDR patients were abnormal (P < 0.01). Of those with PDR, 4 had elevated MCA and 3 had elevated OA velocities while supine at rest.

CONCLUSIONS Patients with PDR demonstrated abnormal hemodynamic responses of the cerebral and ophthalmic circulation both at rest and with exercise.