title: Impaired retinal vasodilator responses in prediabetes and type 2 diabetes.
abstract: OBJECTIVE
  In diabetes, endothelial dysfunction and subsequent structural damage to blood vessels can lead to heart attacks, retinopathy and strokes. However, it is unclear whether prediabetic subjects exhibit microvascular dysfunction indicating early stages of arteriosclerosis and vascular risk. The purpose of this study was to examine whether retinal reactivity may be impaired early in the hyperglycaemic continuum and may be associated with markers of inflammation.
  
  
  METHODS
  Individuals with prediabetes (n = 22), type 2 diabetes (n = 25) and healthy age and body composition matched controls (n = 19) were studied. We used the Dynamic Vessel Analyzer to assess retinal vasoreactivity (percentage change in vessel diameter) during a flickering light stimulation. Fasting highly sensitive c-reactive protein (hs-CRP), a marker of inflammation, was measured in blood plasma.
  
  
  RESULTS
  Prediabetic and diabetic individuals had attenuated peak vasodilator and relative amplitude changes in retinal vein diameters to the flickering light stimulus compared with healthy controls (peak dilation: prediabetic subjects 3.3 ± 1.8%, diabetic subjects 3.3 ± 2.1% and controls 5.6 ± 2.6%, p = 0.001; relative amplitude: prediabetic subjects 4.3 ± 2.2%, diabetic subjects 5.0 ± 2.6% and control subjects 7.2 ± 3.2%, p = 0.003). Similar findings were observed in retinal arteries. Levels of hs-CRP were not associated with either retinal vessel response parameters.
  
  
  CONCLUSIONS
  Retinal reactivity was impaired in prediabetic and type 2 diabetic individuals in parallel with reduced insulin sensitivity but not associated with levels of hs-CRP. Retinal vasoreactivity measurements may be a sensitive tool to assess early vascular risk.
authors.affiliation: Heart and Vascular Institute, Penn State Hershey Medical Center, Pennsylvania, USA. mlott@hmc.psu.edu
authors.forename: Mary E J
authors.initials: ME
authors.lastname: Lott
authors.forename: Julia E
authors.initials: JE
authors.lastname: Slocomb
authors.forename: Vikram
authors.initials: V
authors.lastname: Shivkumar
authors.forename: Bruce
authors.initials: B
authors.lastname: Smith
authors.forename: David
authors.initials: D
authors.lastname: Quillen
authors.forename: Robert A
authors.initials: RA
authors.lastname: Gabbay
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Gardner
authors.forename: Kerstin
authors.initials: K
authors.lastname: Bettermann
mesh_terms: D001794:Blood Pressure / Q000502:physiology; D002097:C-Reactive Protein / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D003930:Diabetic Retinopathy / Q000503:physiopathology*; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D011236:Prediabetic State / Q000503:physiopathology*; D012039:Regional Blood Flow; D012171:Retinal Vessels / Q000503:physiopathology* / Q000528:radiation effects; D014664:Vasodilation / Q000502:physiology* / Q000528:radiation effects
chemical_list: D002097:C-Reactive Protein; D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human
keywords: flickering light stimulation; prediabetes; retinal reactivity; type 2 diabetes; vasodilation