Effect of dapagliflozin on electrocardiographic arrhythmic markers in patients with type 2 diabetes mellitus

Aims Arrhythmic risk is elevated in type 2 diabetes mellitus (T2DM) partly because of abnormal ventricular repolarization. Sodium‐glucose cotransporter‐2 (SGLT‐2) inhibitors may favourably modify electrophysiological properties beyond their glycaemic effects. We aimed to evaluate the association between dapagliflozin initiation and changes in ECG‐derived arrhythmic markers in SGLT‐2 inhibitor‐naive patients with T2DM. Methods In this prospective, non‐randomized, controlled observational study, 700 T2DM patients (350 dapagliflozin, 350 control) were enrolled between June 2023 and February 2026 at a single tertiary‐care center. Dapagliflozin was initiated as part of routine clinical care; controls continued existing antidiabetic therapy. Twelve‐lead ECGs and echocardiograms were obtained at baseline and after 3 months. Primary outcomes were changes in QT interval, QTc, QT dispersion, Tp‐e interval, Tp‐e/QT ratio and Tp‐e/QTc ratio. All 700 enrolled patients completed 3‐month follow‐up. Results At 3 months, the dapagliflozin group showed significant reductions in QT (−8.8 ms), QTc (−10.1 ms), QTd (−5.1 ms), Tp‐e (−6.2 ms), Tp‐e/QT (−0.012) and Tp‐e/QTc (−0.010) (all p < .001), whereas no clinically meaningful changes occurred in controls. Between‐group delta comparisons confirmed significantly greater reductions with dapagliflozin (all p < .001; Cohen's d : 0.48–1.08). Reduction in Tp‐e correlated weakly with HbA1c improvement ( r = −0.145, p = .037, r 2 ≈ 2%); the Tp‐e/QT vs . HbA1c correlation did not reach statistical significance ( r = −0.147, p = .086). Left ventricular ejection fraction (LVEF) improved modestly (+0.8%, p = .003), and left atrial diameter decreased (−0.6 mm, p < .001). Conclusion Three months of dapagliflozin therapy was associated with improvements in multiple ECG‐based arrhythmic markers in patients T2DM.