title: Ocular blood flow analysis detects microvascular abnormalities in impaired glucose tolerance.
abstract: OBJECTIVE
  Waveform analysis has been used to assess vascular resistance and predict cardiovascular events. We aimed to identify microvascular abnormalities in patients with IGT using ocular waveform analysis. The effects of pioglitazone were also assessed.
  
  
  METHODS
  Forty patients with IGT and 24 controls were studied. Doppler velocity recordings were obtained from the central retinal, ophthalmic, and common carotid arteries, and sampled at 200 Hz. A discrete wavelet-based analysis method was employed to quantify waveforms. The RI was also determined. Patients with IGT were randomized to pioglitazone or placebo, and measurements were repeated after 12-week treatment.
  
  
  RESULTS
  In the ocular waveforms, significant differences in power spectra were observed in frequency band 4 (corresponding to frequencies between 6.25 and 12.50 Hz) between groups (p < 0.05). No differences in RI occurred. No association was observed between waveform parameters and fasting glucose or insulin resistance. Pioglitazone had no effect on waveform structure, despite significantly reducing insulin resistance, fasting glucose, and triglycerides (p < 0.05).
  
  
  CONCLUSIONS
  Analysis of ocular Doppler flow waveforms using the discrete wavelet transform identified microvascular abnormalities that were not apparent using RI. Pioglitazone improved glucose, insulin sensitivity, and triglycerides without influencing the contour of the waveforms.
authors.affiliation: Department of Therapeutics and Pharmacology, Queen's University Belfast, Belfast, UK.
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Quinn
authors.forename: Paul K
authors.initials: PK
authors.lastname: Hamilton
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: McCann
authors.forename: Christina E
authors.initials: CE
authors.lastname: Agnew
authors.forename: Auleen M
authors.initials: AM
authors.lastname: Millar
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Lockhart
authors.forename: Mark T
authors.initials: MT
authors.lastname: Harbinson
authors.forename: Gary E
authors.initials: GE
authors.lastname: McVeigh
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000378:metabolism; D005123:Eye / Q000098:blood supply / Q000503:physiopathology; D005215:Fasting; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D007333:Insulin Resistance; D008297:Male; D008833:Microcirculation / Q000187:drug effects*; D055806:Microvessels / Q000002:abnormalities* / Q000503:physiopathology*; D008875:Middle Aged; D000077205:Pioglitazone; D045162:Thiazolidinediones / Q000008:administration & dosage*
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D045162:Thiazolidinediones; D000077205:Pioglitazone