Influence of hypertension and type 2 diabetes mellitus on cerebrovascular reactivity in diabetics with retinopathy

BACKGROUND AND OBJECTIVES: Cerebrovascular reactivity (CVR) provides information on the intracerebral arterioles capacity to react to vasodilatory stimuli. The current study aimed to investigate the influence of hypertension and type 2 diabetes mellitus on CVR in diabetics with retinopathy. DESIGN AND SETTING: Retrospective analysis of data prospectively collected over a 1-year period. SUBJECTS AND METHODS: Subjects were classified into four groups each comprised of 30 participants: diabetic retinopathy with hypertension (DRH), diabetic retinopathy without hypertension (DR), hypertension without diabetes mellitus (H), and healthy controls without diabetes and hypertension (C). CVR was estimated in relation to the increase in the mean flow velocity compared with the basal velocity in both middle cerebral arteries during hypercapnia. RESULTS: In the DRH group, the mean (SD) increase in CVR was 8.8 (2.49) cm/s, in the H group 14.4 (2.59) cm/s and in the DR group 9.7 (2.97) cm/s. The analysis of variance showed significant differences among the groups in blood flow velocity after a breath-holding test (F=89.83; df=3.116; P<.001). CONCLUSIONS: Diabetes mellitus influences CVR more than hypertension.