Abstract

Objective: Flicker-light induced retinal vasodilation may reflect endothelial function in the retinal circulation. We investigated flicker-light induced vasodilation in persons with diabetes and diabetic retinopathy (DR).

Research Design and Methods: Participants consisted of 224 persons with diabetes and 103 non-diabetic controls. Flicker-light induced retinal vasodilation (percentage increase over baseline diameter) was measured using the Dynamic Vessel Analyzer. DR was graded from retinal photographs.

Results: Mean age was 56.5 (±11.8) years in those with diabetes, and 48.0 (±16.3) years in controls. Mean arteriolar and venular dilation after flicker-light stimulation were reduced in persons with diabetes than controls (1.43% [±2.10] vs. 3.46% [±2.36], p<0.001 for arteriolar, and 2.83% [±2.10] vs. 3.98% [±1.84], p<0.001 for venular dilation). After adjusting for age, gender, diabetes duration, fasting glucose, cholesterol and triglyceride levels, current smoking status, systolic blood pressure, use of anti-hypertensive and lipid-lowering medications, persons with reduced flicker-light induced vasodilation were more likely to have diabetes (odds ratio [OR] 19.7, 95% confidence interval [CI] 6.5-59.1, p<0.001, and OR 8.14, 95% CI 3.1-21.4, p<0.001, comparing lowest vs. highest tertile of arteriolar and venular dilation respectively). Diabetic persons with reduced flicker-light induced vasodilation were more likely to have DR (OR 2.2, 95% CI 1.2-4.0, p=0.01 for arteriolar dilation; and OR 2.5, 95% CI 1.3-4.5, p=0.004, for venular dilation).

Conclusions: Reduced retinal vasodilation after flicker-light stimulation is independently associated with diabetes status and, in persons with diabetes, with DR. Our findings may therefore support endothelial dysfunction as a pathophysiological mechanism underlying diabetes and its microvascular manifestations.