Ocular hyperperfusion following onset of intensified insulin therapy is inversely correlated with plasma endothelin-1 in Type I diabetes

AIMS/HYPOTHESIS: It has been reported that improvement of metabolic control by intensified insulin therapy in patients with Type I (insulin-dependent) diabetes mellitus is associated with alterations in ocular blood flow. We hypothesized that these changes in ocular blood flow could be associated with alterations of plasma insulin, glucose or endothelin concentration. METHODS: In 16 patients with Type I diabetes ocular haemodynamic parameters were assessed daily during the first 5 days of institution of intensified insulin therapy and plasma concentrations of glucose, insulin, and endothelin-1 plasma were measured. Retinal white blood cell flux was estimated with the blue field entoptic technique. Pulsatile choroidal blood flow was assessed by laser interferometric measurement of fundus pulsation amplitude. RESULTS: Retinal white blood cell flux ( p=0.0015) and ocular fundus pulsation amplitude ( p<0.001) increased during institution of strict metabolic control. Changes in ocular haemodynamic variables were inversely correlated with concentrations of plasma ET-1, but not with that of insulin or glucose. CONCLUSIONS/INTERPRETATION: These data indicate that institution of improved metabolic status is paralleled by rapid changes in the production of ET-1, which could in turn affect ocular perfusion.