title: The relation of glucose metabolism to left ventricular mass and function and sympathetic nervous system activity in obese subjects with metabolic syndrome.
abstract: BACKGROUND
  Altered cardiac structure and function have been reported in prediabetic and diabetic populations; however, the contribution of the sympathetic nervous system (SNS) to these changes has yet to be delineated.
  
  
  OBJECTIVE
  Our objective was to examine interrelationships between glucose metabolism, left ventricular mass and function, and SNS activity in obese metabolic syndrome subjects.
  
  
  METHODS
  Unmedicated impaired glucose tolerant (IGT) (n = 31) or treatment-naive type 2 diabetic (T2D) (n = 25) subjects, matched for age (mean 58 ± 1 years), gender, body mass index (32.2 ± 0.5 kg/m(2)), and blood pressure, participated. They underwent echocardiography and assessments of whole-body norepinephrine kinetics, muscle sympathetic nerve activity, and insulin sensitivity by euglycemic clamp (M value).
  
  
  RESULTS
  T2D subjects had higher left ventricular mass index (LVMI) (93.6 ± 3.5 vs 77.2 ± 3.4 g/m(2), P = .002) and Doppler-derived isovolumetric relaxation and deceleration times (both P < .05) and lower early/late transmitral inflow velocities (E/A) (P = .02) compared with IGT. Total muscle sympathetic nerve activity and arterial norepinephrine concentration were higher in the T2D group (by 18% and 32%, respectively, both P ≤ .05), whereas plasma norepinephrine clearance was reduced (1.94 ± 0.11 vs 2.26 ± 0.10 L/min, P = .02). M value correlated inversely with left ventricular septal thickness (r = -0.46, P = .007). Whole-body noradrenaline spillover rate correlated with LVMI in the T2D subgroup (r = 0.47, P = .03). In the pooled cohort, LVMI was independently predicted by pulse pressure (r = 0.38, P = .004) and E/A ratio by 2-hour glucose (r = -0.38, P = .005).
  
  
  CONCLUSIONS
  Transition from IGT to T2D is associated with cardiac enlargement and diastolic dysfunction, which relate to metabolic, hemodynamic, and SNS alterations.
authors.affiliation: Laboratories of Human Neurotransmitters, Baker IDI Heart and Diabetes Institute, PO Box 6492, St. Kilda Road Central, Melbourne, Victoria, Australia. A. Nora.Straznicky@bakeridi.edu.au
authors.forename: Nora E
authors.initials: NE
authors.lastname: Straznicky
authors.forename: Mariee T
authors.initials: MT
authors.lastname: Grima
authors.forename: Carolina I
authors.initials: CI
authors.lastname: Sari
authors.forename: Sofie
authors.initials: S
authors.lastname: Karapanagiotidis
authors.forename: Chiew
authors.initials: C
authors.lastname: Wong
authors.forename: Nina
authors.initials: N
authors.lastname: Eikelis
authors.forename: Katrina L
authors.initials: KL
authors.lastname: Richards
authors.forename: Geraldine
authors.initials: G
authors.lastname: Lee
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Nestel
authors.forename: John B
authors.initials: JB
authors.lastname: Dixon
authors.forename: Gavin W
authors.initials: GW
authors.lastname: Lambert
authors.forename: Markus P
authors.initials: MP
authors.lastname: Schlaich
authors.forename: Elisabeth A
authors.initials: EA
authors.lastname: Lambert
mesh_terms: D001794:Blood Pressure / Q000502:physiology; D015992:Body Mass Index; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000378:metabolism / Q000503:physiopathology; D005260:Female; D005947:Glucose / Q000378:metabolism*; D015309:Glucose Clamp Technique; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D024821:Metabolic Syndrome / Q000150:complications / Q000378:metabolism* / Q000503:physiopathology; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism / Q000503:physiopathology; D009638:Norepinephrine / Q000378:metabolism; D009765:Obesity / Q000150:complications / Q000378:metabolism* / Q000503:physiopathology; D013564:Sympathetic Nervous System / Q000378:metabolism / Q000503:physiopathology*; D014463:Ultrasonography; D016277:Ventricular Function, Left / Q000502:physiology*
chemical_list: D005947:Glucose; D009638:Norepinephrine