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, r2 ≈ 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.