Endothelial perturbation: a link between non-dipping and retinopathy in type 2 diabetes?

Reduced diurnal blood pressure (BP) variation ("non-dipping") is associated with both micro- and macrovascular complications in patients with type 2 diabetes. The relation between endothelial perturbation and diurnal BP variation in diabetic subjects has not previously been studied. Seventy-six subjects, stratified to 4 gender-, age-, and duration-matched groups of 19 subjects each, were studied (group A: non-diabetic subjects; group B to D, type 2 diabetic subjects; group B: no retinopathy; group C: minimal background retinopathy; group D: diabetic maculopathy). All subjects underwent a 24-hour ambulatory BP monitoring. von Willebrand factor (vWF), fibrinogen, E-selectin, and intercellular adhesion molecule-1 were measured in plasma. Systolic night/day BP ratio increased gradually in groups A to D: 85.2 +/- 5%, 85.7 +/- 7%, 88.5 +/- 6%, and 90.5 +/- 7%, respectively, P < .05. Among diabetic patients, non-dippers had significantly higher plasma levels of vWF and fibrinogen than dippers (median/interquartile range 1.7/1.4 to 2.1 vs. 1.2/0.9 to 1.5 U/mL, P < .01 and 3.6/3.6 to 3.7 vs. 2.9/2.5 to 3.6 g/L, P = .01). Non-dipping is associated with elevated plasma levels of proteins related to endothelial cell activation as well as with retinopathy in subjects with type 2 diabetes. This finding suggests a possible mechanism linking non-dipping with microvascular complications in these subjects.