title: Cardiac autonomic nervous dysfunction detected by both heart rate variability and heart rate turbulence in prediabetic patients with isolated impaired fasting glucose.
abstract: Cardiac autonomic nervous dysfunction (CAND), a severe complication of diabetes, has also been shown to affect prediabetic patients. The role of isolated impaired fasting plasma glucose (IFG), a subtype of prediabetes, is not clear in the pathogenesis of CAND. The aim of this study was to examine the relationship between isolated IFG and cardiac autonomic function using heart rate variability (HRV) and heart rate turbulence (HRT) indices derived from 24-h Holter electrocardiogram recordings.
  
  
  
  This observational, prospective, cross-sectional study examined 400 consecutive subjects divided into three groups according to oral glucose tolerance test results: the control group [Group I, fasting plasma glucose (FPG) <100 mg/dL and normal glucose tolerance, n=193], the isolated IFG group (Group II, FPG ≥100 and <126 mg/dL, n=134), and the isolated impaired glucose tolerance (IGT), both IFG and IGT, or newly diagnosed diabetes' group (Group III, n=73). Patients with non-sinus rhythm, known diabetes mellitus, coronary artery disease, heart failure, severe valvular disease, or receiving medical therapy that may affect HRV and HRT indices were excluded. Time domain HRV parameters, turbulence onset (TO), turbulence slope (TS), and HRT category were examined. Chi-square, one-way analysis of variance, Kruskal-Wallis H, and Mann-Whitney U tests were used to compare variables where appropriate. The correlation between Holter data and FPG levels was analyzed using the Spearman's test. Multiple linear regression analysis was performed to identify independent predictors of the HRV and HRT parameters.
  
  
  
  Median (interquartile range 25-75) FPG levels in Groups I, II, and III were 89 (83/93) mg/dL, 109 (104/116) mg/dL, and 174 (150.5/197) mg/dL, respectively. There were significant differences in HRV and HRT parameters between and among all groups. While HRV parameters and TS decreased from Group I to Group III, TO and HRT category gradually increased. Additionally, FPG level was significantly correlated with SDNN, r=-0.220; SDNN index, r=-0.192; SDANN, r=-0.207; RMSSD, r=-0.228; pNN50, r=-0.226; TO, r=0.354; and TS, r=-0.331 (all p<0.001).
  
  
  
  CAND, as detected by both HRV and HRT, appear to be present in the isolated IFG subtype of prediabetes.
authors.affiliation: Department of Cardiology, Medical and Research Center of Alanya, Başkent University, Alanya, Antalya-Turkey. serhatbalcioglu@gmail.com.
authors.forename: Akif Serhat
authors.initials: AS
authors.lastname: Balcıoğlu
authors.affiliation: Department of Cardiology, Medical and Research Center of Alanya, Başkent University, Alanya, Antalya-Turkey.
authors.forename: Sinan
authors.initials: S
authors.lastname: Akıncı
authors.affiliation: Department of Cardiology, Medical and Research Center of Alanya, Başkent University, Alanya, Antalya-Turkey.
authors.forename: Davran
authors.initials: D
authors.lastname: Çiçek
authors.affiliation: Department of Cardiology, Medical and Research Center of Alanya, Başkent University, Alanya, Antalya-Turkey.
authors.forename: Ali
authors.initials: A
authors.lastname: Çoner
authors.affiliation: Department of Cardiology, Faculty of Medicine, Başkent University, Ankara-Turkey.
authors.forename: Uğur Abbas
authors.initials: UA
authors.lastname: Bal
authors.affiliation: Department of Cardiology, Faculty of Medicine, Başkent University, Ankara-Turkey.
authors.forename: İbrahim Haldun
authors.initials: İH
authors.lastname: Müderrisoğlu
mesh_terms: D001341:Autonomic Nervous System / Q000503:physiopathology*; D001786:Blood Glucose; D003430:Cross-Sectional Studies; D048909:Diabetes Complications / Q000175:diagnosis*; D005215:Fasting; D006331:Heart Diseases / Q000175:diagnosis*; D006339:Heart Rate; D006801:Humans; D011446:Prospective Studies
chemical_list: D001786:Blood Glucose