Abstract
Purpose: :
Diabetic retinopathy is a severe and specific microvascular complication which it can lead to blindness. Previous studies have reported the presence of vascular abnormalities before the clinical onset of diabetic retinopathy, especially an early endothelial dysfunction. This dysfunction appears in retinal vessels as a decrease of a flicker-induced vasodilation and in skin microvasculature as a decrease of an endothelium-dependent vasodilation. Nevertheless, the link between endothelial function in retinal and skin microvasculature remains poorly studied. The purpose was to assess microcirculation in young type 1 diabetes, without clinical diabetic retinopathy and in controls.
Methods: :
Nineteen young patients with a type 1 diabetes and neither diabetic retinopathy nor hypertension, and seventeen sex matched healthy controls were included. We used the Retinal Vessel Analyser to continuously measure retinal vessels diameters at baseline, after sublingual administration of nitroglycerin, an exogenous nitric oxide donor (endothelium-independent vasodilation) and after flickering light stimulation (endothelium-dependent vasodilation). To explore the cutaneous perfusion, we used laser Doppler flowmetry accompanied by iontophoresis of acetylcholine, to assess microcirculation endothelial function and then by hyperemia heat-induced to investigate endothelium-independent vasodilation.
Results: :
At baseline, both retinal arterioles and venules diameters were higher in patients with diabetes than in healthy subjects. After nitroglycerin administration, although arterioles and venules maximal vasodilation was significant in controls, we did not observe a significant vasodilation in patients with diabetes. Stimulation with flicker induced an arteriolar vasodilation less important in patients than in controls. The skin microcirculation assessments reveals a significant decrease of acetylcholine response and of heat vasodilation in patients with diabetes compared to controls.
Conclusions: :
Before the clinical onset of microvascular impairment (diabetic retinopathy), in this population, there is a morphological impairment consisting in an arteriolar and venular vasodilatation at baseline. There is also a functional impairment consisting in a retinal and cutaneous endothelial dysfunction proved by a decrease of flicker-induced vasodilation and of the acetylcholine-induced response. There is also a decrease of maximal vasodilatory capacity revealed by a decrease of retinal and skin vasodilation induced by nitroglycerin and heat.
Clinical Trial: :
http://www.clinicaltrials.gov NCT01097551
Keywords: diabetes • imaging/image analysis: clinical • nitric oxide