title: [Circadian rhythm of QT- and QTc-intervals in diabetics and hypertensives].
abstract: Few studies have been done on the circadian rhythm of QT- und corrected QT-interval in diabetics.
  
  
  METHODS
  13 type II diabetics (mean duration 10.08 yrs +/- 1.95 (SEM), 12 insulin-dependent) and 13 hypertensives, mean age 58.2 +/- 197 (SEM) and 57.3 +/- 1.4 yrs (p = n.s.), respectively, without cardiovascular events within the last 6 months before rehabilitation underwent Holter monitoring. We investigated mean and maximum QT-interval, QTc-interval (Bazett-formula), RR-interval as well as spectral parameters LF, HF, and LF/HF ratio.
  
  
  RESULTS
  Both groups showed significant circadian variations of mean and maximum QT-intervals. No group differences were found. There was no significant circadian rhythm of mean or maximum QTc-interval. Diabetics had significantly prolonged maximum QTc-intervals during the day-time. Mean and maximum RR-intervals in diabetics were significantly shorter. Both groups showed a significant circadian rhythm. LF and HF were significantly shorter in diabetics. Only in diabetics could significant circadian rhythm of LF and HF be demonstrated. The LF/HF ratio was significantly shorter in diabetics. The hypertensive group showed a decreasing circadian trend whereas diabetics showed increasing LF/HF ratio trend.
  
  
  CONCLUSIONS
  Mean and maximum QT-intervals are significantly shorter in diabetics than in hypertensives. Maximum QTc-interval prolongation is highly significant (p < 0.01) in diabetics. Spectral parameters LF and HF are reduced in comparison with hypertensives. The prolongation of the maximum QTc-interval could be expression of an increased arrythmogenic and cardiovascular risk in diabetics.
authors.affiliation: Rehabilitationsklinik Wetterau der BfA Zanderstr. 30-32 61231 Bad Nauheim, Germany. DSeyfert@t-online.de
authors.forename: H
authors.initials: H
authors.lastname: Seyfert
authors.forename: T
authors.initials: T
authors.lastname: Wendt
mesh_terms: D000959:Antihypertensive Agents / Q000627:therapeutic use; D002940:Circadian Rhythm; D003627:Data Interpretation, Statistical; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000188:drug therapy / Q000503:physiopathology*; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000188:drug therapy / Q000503:physiopathology*; D007004:Hypoglycemic Agents / Q000627:therapeutic use; D007328:Insulin / Q000008:administration & dosage / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012307:Risk Factors
chemical_list: D000959:Antihypertensive Agents; D007004:Hypoglycemic Agents; D007328:Insulin
vernacular_title: Zirkadianer Rhythmus von QT- und QTc-Intervallen bei Hypertonikern und Diabetikern.