Effects of Prediabetes on Ventricular Repolarization Markers in Electrocardiography

The blood glucose levels in people with prediabetes mellitus (PDM) are regarded as too high to be normal but below the cutoff for diabetes mellitus (DM). Clinical indicators for PDM patients include impaired glucose tolerance (IGT), impaired fasting glucose (IFG), and/or hemoglobin A1c (HbA1c) levels between 5.7 and 6.4% (39-47 mmol/mol). PDM has been shown to raises the risk of cardiovascular disease (CVD) and mortality. Meanwhile, death and morbidity can be predicted by the new ventricular repolarization features of the electrocardiogram (ECG). Several studies have analyzed the connection between DM and the ventricular repolarization characteristics of ECG; however, few studies have examined the connection between PDM and these ventricular repolarization characteristics. This study evaluated the ECG ventricular repolarization parameters in individuals with PDM.

A retrospective case-control design was used. Randomly selected participants included 79 PDM patients (30 men, mean age: 39.7 ± 5.7 years) and 79 controls (30 men, mean age: 39.8 ± 5.2 years). ECG intervals analyzed were the distance from the beginning of the Q wave to the end of the T wave (QT), the distance between Q and S waves (QRS), the distance between the T wave's termination and point J (JT), and the distance between the peak and endpoint of the T wave (Tp-e), along with corrected and derived measures (corrected QT interval (QTc), the difference between the maximum and smallest QT intervals (QTd), corrected QTd (QTdc), corrected JT interval (JTc), Tp-e/QT, Tp-e/QTc, Tp-e/JT, Tp-e/JTc). Patient records were retrieved from the institution's database.

Both groups had comparable averages for age, gender, smoking, hyperlipidemia, body mass index (BMI), (p > 0.05 for each). Similarly, both groups had similar QT, QRS, and JT intervals. PDM patients had significantly greater heart rates (bpm), and QTc, QTd, QTdc, JTc, and Tp-e intervals (millisecond, ms) than the control group. The results were deemed significant when HbA1c levels were associated with every employed ECG measurement in our investigation.

In our study, the HbA1c value was shown to be moderately positively correlated with the heart rate and QTc, QTd, QTdc, JTc, and Tp-e intervals, all of which were determined to be significant. Additionally, the HbA1c value showed a weak positive correlation with Tp-e/QT, Tp-e/JT ratios, which were statistically significant. This study showed that patients with PDM are prone to ventricular arrhythmia in the early period of the disorder.