title: Alterations in heart rate variability during everyday life are linked to insulin resistance. A role of dominating sympathetic over parasympathetic nerve activity?
abstract: OBJECTIVE
  To evaluate the role of the autonomic nervous system (ANS) in the development of insulin resistance (IR) and assess the relationship between IR and activity of ANS using power spectrum analysis of heart rate variability (HRV).
  
  
  METHODS
  Twenty-three healthy first-degree relatives of patients with type 2 diabetes (R) and 24 control subjects without family history of diabetes (C) group-matched for age, BMI and sex were included. Insulin sensitivity (M value) was assessed by hyperinsulinemic (56 mU/m(2)/min) euglycemic clamp. Activity of the ANS was assessed using power spectrum analysis of HRV in long-term recordings, i.e., 24-h ECG monitoring, and in short-term recordings during manoeuvres activating the ANS. Computed tomography was performed to estimate the amount and distribution of abdominal adipose tissue.
  
  
  RESULTS
  Insulin sensitivity (M value, mg/kg lbm/min) did not differ significantly between the R and C groups. Total spectral power (Ptot) and very low-frequency (PVLF) power was lower in R than C during 24 h ECG-recordings (p = 0.02 and p = 0.03). The best fit multiple variable linear regression model (r(2) = 0.37, p < 0.001 for model) indicated that body composition (BMI) and long-term low to high frequency (LF/HF) power ratio (std β = -0.46, p = 0.001 and std β = -0.28, p = 0.003, respectively) were significantly and independently associated with the M value.
  
  
  CONCLUSIONS
  Altered heart rate variability, assessed by power spectrum analysis, during everyday life is linked to insulin resistance. The data suggest that an increased ratio of sympathetic to parasympathetic nerve activity, occurring via both inherited and acquired mechanisms, could potentially contribute to the development of type 2 diabetes.
authors.affiliation: Department of Medical Sciences, Uppsala University Hospital, 751 85, Uppsala, Sweden. maria.k.svensson@medsci.uu.se.
authors.forename: Maria K
authors.initials: MK
authors.lastname: Svensson
authors.affiliation: Department of Medicine, Umeå University Hospital, Umeå, Sweden.
authors.forename: Stina
authors.initials: S
authors.lastname: Lindmark
authors.affiliation: Department of Biomedical Engineering & Informatics, Umeå University Hospital, Umeå, Sweden.
authors.forename: Urban
authors.initials: U
authors.lastname: Wiklund
authors.affiliation: Department of Clinical Physiology, Örebro University Hospital, Örebro, Sweden.
authors.forename: Peter
authors.initials: P
authors.lastname: Rask
authors.affiliation: Department of Biomedical Engineering & Informatics, Umeå University Hospital, Umeå, Sweden.
authors.forename: Marcus
authors.initials: M
authors.lastname: Karlsson
authors.affiliation: Department of Clinical Physiology, Örebro University Hospital, Örebro, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Myrin
authors.affiliation: Department of Radiology, Uppsala University Hospital, Uppsala, Sweden.
authors.forename: Joel
authors.initials: J
authors.lastname: Kullberg
authors.affiliation: Department of Radiology, Uppsala University Hospital, Uppsala, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Johansson
authors.affiliation: Department of Medical Sciences, Uppsala University Hospital, 751 85, Uppsala, Sweden.
authors.forename: Jan W
authors.initials: JW
authors.lastname: Eriksson
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000378:metabolism / Q000503:physiopathology*; D001786:Blood Glucose / Q000502:physiology*; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism / Q000503:physiopathology*; D004562:Electrocardiography / Q000379:methods; D005260:Female; D015309:Glucose Clamp Technique; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged
chemical_list: D001786:Blood Glucose
keywords: Autonomic nervous system; Heart rate variability; Insulin sensitivity; Spectral analysis; Type 2 diabetes