title: von Willebrand factor and retinal circulation in early-stage retinopathy of type 1 diabetes.
abstract: OBJECTIVE
  Although retinopathy is a common microvascular complication of type 1 diabetes, the mechanism for this complication is still unknown. Changes in retinal circulation have been noted before the development of overt retinal pathology. Because von Willebrand factor (vWF) is a marker for endothelial dysfunction and mediates platelet adhesion, we determined if there was an association between vWF and retinal circulation in the early stages of diabetic retinopathy.
  
  
  METHODS
  Twenty subjects (aged 32.4 +/- 7.8 years) with type 1 diabetes and minimal or no retinopathy were studied. The mean duration of diabetes was 4.7 +/- 2.6 years. Data were collected at baseline and after 4 months of 1,800 IU vitamin E therapy or placebo. Retinal circulation was evaluated by video fluorescein angiography. Plasma vWF antigen levels were measured by enzyme-linked immunosorbent assay and fibrinogen by the Clauss method.
  
  
  RESULTS
  Retinal blood flow was negatively correlated with vWF levels (r = -0.44, P = 0.008), whereas retinal circulation time was positively correlated with vWF levels (r = 0.33, P = 0.048). Fibrinogen levels were not significantly associated with either retinal index. However, fibrinogen levels were positively associated with HbA1c levels (r = 0.34, P = 0.01), indicating an association between poor glycemic control and higher fibrinogen levels.
  
  
  CONCLUSIONS
  Increased vWF was associated with a prolonged retinal circulation time and reduced retinal blood flow in early-stage retinopathy of type 1 diabetes. Reduced blood flow associated with increased vWF levels may promote stasis in the retinal circulation and lead to local hypoxemia. These changes might contribute to the microvascular complications of diabetes. Whether the vWF levels predict retinal complications deserves further investigation.
authors.affiliation: Institute for Prevention of Cardiovascular Disease, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA. dfeng2@caregroup.harvard.edu
authors.forename: D
authors.initials: D
authors.lastname: Feng
authors.forename: S E
authors.initials: SE
authors.lastname: Bursell
authors.forename: A C
authors.initials: AC
authors.lastname: Clermont
authors.forename: I
authors.initials: I
authors.lastname: Lipinska
authors.forename: L P
authors.initials: LP
authors.lastname: Aiello
authors.forename: L
authors.initials: L
authors.lastname: Laffel
authors.forename: G L
authors.initials: GL
authors.lastname: King
authors.forename: G H
authors.initials: GH
authors.lastname: Tofler
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000032:analysis; D018592:Cross-Over Studies; D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000188:drug therapy / Q000503:physiopathology* / Q000517:prevention & control; D004311:Double-Blind Method; D005260:Female; D005340:Fibrinogen / Q000032:analysis; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D008297:Male; D012039:Regional Blood Flow / Q000187:drug effects; D012044:Regression Analysis; D012171:Retinal Vessels / Q000187:drug effects / Q000503:physiopathology*; D014810:Vitamin E / Q000097:blood / Q000627:therapeutic use*; D014841:von Willebrand Factor / Q000032:analysis*
chemical_list: D015415:Biomarkers; D005340:Fibrinogen; D006442:Glycated Hemoglobin; D014810:Vitamin E; D014841:von Willebrand Factor