Corrected QT interval in relation to the severity of diabetic autonomic neuropathy

Abstract

The aim of this study was to investigate to what extent the existence of objective signs of diabetic autonomic neuropathy affects the corrected QT interval (QTc) in diabetic subjects. A total of 105 diabetic subjects (type 1, n = 53; type 2, n = 52) as well as 40 matched (by age and sex) control subjects were studied. All subjects underwent the battery of five Ewing tests. Autonomic neuropathy was diagnosed if two of the five tests were abnormal. In addition, the result of each test was considered as normal (grade = 0), borderline (grade = 1) or abnormal (grade = 2), and on the basis of the sum of the scores we calculated a total score for autonomic neuropathy. The QTc interval was measured at rest, and a value > 440 ms was considered abnormal. The QTc interval was significantly more prolonged in diabetic persons with autonomic neuropathy than in those without neutopathy and in control subjects: 408.4 +/- 24.2 ms vs. 394.6 +/- 27.9 ms and 393.6 +/- 25.5 ms respectively (P = 0.001). Furthermore, multivariate analysis controlling for age, sex, systolic and diastolic blood pressure, body mass index (BMI), waist-hip ratio (WHR), smoking, type and duration of diabetes, type of treatment, HBA1c and total score of autonomic neuropathy eliminated the role of all these factors as potential confounders except for the total score of autonomic neuropathy, which was found to affect QTc interval independently and significantly (P = 0.012). In summary, the present study confirmed the well-known relation between autonomic neuropathy and QTc interval; in addition, it showed that QTc prolongation is associated with major degrees of autonomic neuropathy.

Relationship Between Autonomic Diabetic Neuropathy and Glycemic Control

“…7,9,10 The prevalence of CAN is reported as 34 % by Ziegler, as 60 % by Pappachan, as 57.5 % by Mehta, as 62 % by Tentolouris and 67.6 % by Thi. 11,12 In our study 46 (92%) of the diabetic patients had mild and severe CAN.…”

Orthostatic Hypotension and Heart Rate Variability as Signs of Cardiac Autonomic Neuropathy in Diabetes Mellitus

“…Abnormal QTc interval is an indicator of sympathetic and parasympathetic nervous system dysfunction (7,12). Although a controversy exists relating to the upper limit of normal of QTc interval, a QT interval over 0.5 seconds definitely necessitates an urgent intervention such as a cardiac evaluation or revision of the treatment (13). Since all cases in this study had QTc values above 0.5 seconds, it is clear that we deal with a population having serious cardiac autonomic neuropathy.…”

“…We found patients with neuropathy induced QTc prolongation up to 0.89 seconds with a median QTc of 0.62. This was astonishing as we know that the mean neuropathy induced QTc prolongation was less than 0.50 seconds in most studies (7,11,12,13).…”

Hyperbaric oxygen therapy reduces the risk of QTc interval prolongation in patients with diabetes and hard-to-heal foot ulcers

“…QTc prolongation is more frequently found in patients with diabetes than in non-diabetic patients [7]. The mechanism behind the higher prevalence of prolonged QTc time among people with diabetes is not fully understood, but possible contributors could be a higher incidence of myocardial infarctions as well as presence of cardiac autonomic neuropathy, factors known to be associated with QTc prolongation [7,20]. Further, it is also known that QT interval is prolonged during hypoglycaemia[23].…”

“…In this study QTc prolongation was defined as a QTc value > 440 milliseconds (ms) [19,20]. We also evaluated the cut-point of 450 ms, since this alternative level also is used in the literature [5,16].…”