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Open Access Highly Accessed Original investigation

Does glycemic control reverse dispersion of ventricular repolarization in type 2 diabetes?

Takayuki Miki1, Toshiyuki Tobisawa1, Tatsuya Sato1, Masaya Tanno1, Toshiyuki Yano1, Hiroshi Akasaka1, Atsushi Kuno12, Makoto Ogasawara1, Hiromichi Murase1, Shigeyuki Saitoh3 and Tetsuji Miura1*

Author Affiliations

1 Department of Cardiovascular, Renal and Metabolic Medicine, Sapporo Medical University School of Medicine, South-1 West-16, Sapporo 060-8543, Chuo-ku, Japan

2 Department of Pharmacology, Sapporo Medical University School of Medicine, Sapporo, Japan

3 Department of Nursing, Sapporo Medical University School of Health Sciences, Sapporo, Japan

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Cardiovascular Diabetology 2014, 13:125  doi:10.1186/s12933-014-0125-8

Published: 21 August 2014

Abstract

Background

Abnormal ventricular repolarization is a predictor of cardiovascular mortality. In this study, we tested the hypothesis that glycemic control reverses abnormal ventricular repolarization in patients with type 2 diabetes.

Methods

We analyzed longitudinal changes in repolarization indices of electrocardiograms in retrospectively enrolled 44 patients with type 2 diabetes and 44 age-matched healthy subjects.

Results

In the diabetic group, BMI was greater, levels of HbA1c (10.0 ± 1.6 vs. 5.6 ± 0.3%) and triglyceride were higher and level of HDL cholesterol was lower than those in the control group. Although mean QTc intervals were similar (413.6 ± 18.5 vs. 408.3 ± 22.7 ms), QT dispersion (41.8 ± 15.4 vs. 28.7 ± 7.7 ms) and Tpeak-Tend in lead V5 (83.6 ± 13.6 vs. 71.3 ± 10.3 ms) were significantly longer in the diabetic group than in the control group, indicating increased heterogeneity of ventricular repolarization in type 2 diabetes. During follow-up of 36 patients in the diabetic group for 787 ± 301 days, HbA1c level decreased to 7.3 ± 1.6%, while BMI did not significantly change. In contrast to HbA1c, QT dispersion (45.8 ± 15.0 ms) and Tpeak-Tend in lead V5 (83.6 ± 10.6 ms) were not significantly reduced during the follow-up period. There was no correlation between the change in HbA1c and the change in QT dispersion or Tpeak-Tend.

Conclusions

Increased heterogeneity of ventricular repolarization in type 2 diabetic patients was not reduced during the relatively short follow-up period despite significantly improved glycemic control.

Keywords:
Type 2 diabetes; Glycemic control; QT dispersion; Ventricular repolarization