title: Acute hyperglycemia does not impair microvascular reactivity and endothelial function during hyperinsulinemic isoglycemic and hyperglycemic clamp in type 1 diabetic patients.
abstract: OBJECTIVE
  The aim of this study was to evaluate the effect of acute glycemia increase on microvasculature and endothelium in Type 1 diabetes during hyperinsulinemic clamp.
  
  
  METHODS
  Sixteen patients (51 ± 7 yrs) without complications were examined during iso- and hyperglycemic clamp (glucose increase 5.5 mmol·L(-1)). Insulin, lipid parameters, cell adhesion molecules and fibrinogen were analyzed. Microvascular reactivity (MVR) was measured by laser Doppler flowmetry.
  
  
  RESULTS
  Maximum perfusion and the velocity of perfusion increase during PORH were higher in hyperglycemia compared to baseline (47 ± 16 versus 40 ± 16 PU, P < 0.01, and 10.4 ± 16.5 versus 2.6 ± 1.5 PU·s(-1), P < 0.05, resp.). Time to the maximum perfusion during TH was shorter and velocity of perfusion increase during TH higher at hyperglycemia compared to isoglycemic phase (69 ± 15 versus 77 ± 16 s, P < 0.05, and 1.4 ± 0.8 versus 1.2 ± 0.7 PU·s(-1), P < 0.05, resp.). An inverse relationship was found between insulinemia and the time to maximum perfusion during PORH (r = -0.70, P = 0.007).
  
  
  CONCLUSIONS
  Acute glycemia did not impair microvascular reactivity in this clamp study in Type 1 diabetic patients. Our results suggest that insulin may play a significant role in the regulation of microvascular perfusion in patients with Type 1 diabetes through its vasodilation effect and can counteract the effect of acute glucose fluctuations.
authors.affiliation: 3rd Department of Internal Medicine, 1st Faculty of Medicine, Charles University, U Nemocnice 1, 12800 Prague, Czech Republic.
authors.forename: Eva
authors.initials: E
authors.lastname: Horová
authors.forename: Jiří
authors.initials: J
authors.lastname: Mazoch
authors.forename: Jiřina
authors.initials: J
authors.lastname: Hiigertová
authors.forename: Jan
authors.initials: J
authors.lastname: Kvasnička
authors.forename: Jan
authors.initials: J
authors.lastname: Skrha
authors.forename: Jan
authors.initials: J
authors.lastname: Soupal
authors.forename: Martin
authors.initials: M
authors.lastname: Prázný
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D002138:Calibration; D048909:Diabetes Complications / Q000473:pathology; D003922:Diabetes Mellitus, Type 1 / Q000503:physiopathology / Q000628:therapy; D004730:Endothelium, Vascular / Q000166:cytology; D015309:Glucose Clamp Technique; D006801:Humans; D006943:Hyperglycemia / Q000503:physiopathology* / Q000628:therapy; D007328:Insulin / Q000378:metabolism; D017078:Laser-Doppler Flowmetry / Q000379:methods; D008833:Microcirculation; D008875:Middle Aged; D018384:Oxidative Stress; D010477:Perfusion
chemical_list: D001786:Blood Glucose; D007328:Insulin