title: Continuous glucose monitoring reveals associations of glucose levels with QT interval length.
abstract: BACKGROUND
  QTc interval lengthening during hypoglycemia is discussed as a mechanism linked to sudden death in diabetes patients and the so-called "dead in bed syndrome." Previous research reported a high interindividual variability in the glucose-QTc association. The present study aimed at deriving parameters for direction and strength of the glucose-QTc association on the patient level using combined Holter electrocardiogram (ECG) and continuous glucose monitoring.
  
  
  METHODS
  Twenty type 1 diabetes patients were studied: mean (SD, range) age, 43.6 (10.8, 22-65) years; gender male (n [%]), 10 (50.0%); mean (SD) hemoglobin A1C, 8.5% (1.0%); and impaired hypoglycemia awareness (n [%]), six (30.0%). Continuous interstitial glucose monitoring and Holter ECG monitoring were performed for 48 h. Hierarchical (mixed) regression modeling was used to account for the structure of the data.
  
  
  RESULTS
  Glucose levels during nighttime were negatively associated with QTc interval length if the data structure was accounted for (b [SE] = -0.76 [0.17], P = 0.000). Exploratory regression analysis revealed hypoglycemia awareness as the only predictor of the individual strength of the glucose-QTc association, with the impaired awareness group showing less evidence for an association of low glucose with QTc lengthening.
  
  
  CONCLUSIONS
  Mixed regression allows for deriving parameters for the glucose-QTc association on the patient level. Consistent with previous studies, we found a large interindividual variability in the glucose-QTc association. The finding on impaired hypoglycemia awareness patients has to be interpreted with caution but provides some support for the role of sympathetic activation for the QTc-glucose link.
authors.affiliation: Institute of Psychology, University of Greifswald, Franz-Mehring-Strasse 47, Greifswald, Germany. kubiak@uni-greifswald.de
authors.forename: T
authors.initials: T
authors.lastname: Kubiak
authors.forename: A
authors.initials: A
authors.lastname: Wittig
authors.forename: C
authors.initials: C
authors.lastname: Koll
authors.forename: B
authors.initials: B
authors.lastname: Mraz
authors.forename: J
authors.initials: J
authors.lastname: Gustav
authors.forename: U
authors.initials: U
authors.lastname: Herrmann
authors.forename: H
authors.initials: H
authors.lastname: Weber
authors.forename: W
authors.initials: W
authors.lastname: Kerner
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000503:physiopathology*; D015716:Electrocardiography, Ambulatory; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D055815:Young Adult
chemical_list: D001786:Blood Glucose