title: Reduced heart rate variability among youth with type 1 diabetes: the SEARCH CVD study.
abstract: OBJECTIVE
  This study compared heart rate variability (HRV) parameters in youth with and without type 1 diabetes and explored potential contributors of altered HRV.
  
  
  METHODS
  HRV parameters were measured among 354 youth with type 1 diabetes (mean age 18.8 years, diabetes duration 9.8 years, and mean A1C 8.9%) and 176 youth without diabetes (mean age 19.2 years) participating in the SEARCH CVD study. Multiple linear regression was used to assess the relationship between diabetes status and HRV parameters, adjusting for covariates.
  
  
  RESULTS
  Compared with control subjects, youth with type 1 diabetes had reduced overall HRV (10.09 ms lower SD of NN intervals [SDNN]) and markers of parasympathetic loss (13.5 ms reduced root mean square successive difference of NN intervals [RMSSD] and 5.2 normalized units (n.u.) reduced high frequency [HF] power) with sympathetic override (5.2 n.u. increased low frequency [LF] power), independent of demographic, anthropometric, and traditional cardiovascular risk factors. Older age, female sex, higher LDL cholesterol and triglyceride levels, and presence of microalbuminuria were independently associated with lower HRV but did not account for the observed differences between youth with and without diabetes. Youth with type 1 diabetes and A1C levels ≥7.5% had significantly worse HRV parameters than control subjects; however, in youth with optimal glycemic control (A1C <7.5%), HRV parameters did not differ significantly from control subjects.
  
  
  CONCLUSIONS
  Youth with type 1 diabetes have signs of early cardiac autonomic neuropathy: reduced overall HRV and parasympathetic loss with sympathetic override. The main driver of these subclinical abnormalities appears to be hyperglycemia.
authors.affiliation: Department of Epidemiology, Colorado School of Public Health, Aurora, CO, USA.
authors.forename: Mamta
authors.initials: M
authors.lastname: Jaiswal
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Urbina
authors.forename: R Paul
authors.initials: RP
authors.lastname: Wadwa
authors.forename: Jennifer W
authors.initials: JW
authors.lastname: Talton
authors.forename: Ralph B
authors.initials: RB
authors.lastname: D'Agostino
authors.forename: Richard F
authors.initials: RF
authors.lastname: Hamman
authors.forename: Tasha E
authors.initials: TE
authors.lastname: Fingerlin
authors.forename: Stephen
authors.initials: S
authors.lastname: Daniels
authors.forename: Santica M
authors.initials: SM
authors.lastname: Marcovina
authors.forename: Lawrence M
authors.initials: LM
authors.lastname: Dolan
authors.forename: Dana
authors.initials: D
authors.lastname: Dabelea
mesh_terms: D000293:Adolescent; D002318:Cardiovascular Diseases / Q000097:blood / Q000503:physiopathology; D008078:Cholesterol, LDL / Q000097:blood; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000503:physiopathology*; D003929:Diabetic Neuropathies / Q000097:blood / Q000503:physiopathology; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D014280:Triglycerides / Q000097:blood; D055815:Young Adult
chemical_list: D008078:Cholesterol, LDL; D014280:Triglycerides