Sodium-glucose cotransporter 2 inhibitors can improve heart failure outcomes, however, the effects on left ventricular (LV) function remain unclear. This prospective observational study aimed to investigate whether initiating empagliflozin therapy was associated with improved LV diastolic function following an acute coronary syndrome (ACS) in patients with type 2 diabetes (T2D). Patients with ACS and T2D were identified during hospitalisation in a cardiology unit. Empagliflozin was initiated at discharge in eligible patients (i.e. HbA1c > 7%) without contraindications or precautions. Transthoracic echocardiography was performed during admission and after 3-6 months. Changes in echocardiographic parameters were compared between patients initiated on empagliflozin versus not initiated on empagliflozin (control). There were 22 patients in each group (n = 44). Baseline characteristics, medications and echocardiographic parameters were similar except HbA1c (empagliflozin: 9.8 ± 1.6% versus control: 6.6 ± 0.7%, p < 0.001). Baseline LV global longitudinal strain (GLS) (empagliflozin: - 12.4 ± 2.8 versus control: - 13.0 ± 3.6%) and ejection fraction (51.1 ± 11.3 versus 54.9 ± 10.8%) were similar. The difference in change from baseline to follow-up was significant for LV mass index (empagliflozin: - 14.1 ± 21.6 versus control: 3.6 ± 18.7 g/m, p = 0.006), left atrial volume index (- 2.1 ± 8.1 versus 3.4 ± 9.5 ml/m, p = 0.045), mitral valve E-wave velocity (- 0.14 ± 0.23 versus 0.03 ± 0.16 m/s, p = 0.007) and average E/e' (- 2.1 ± 2.6 versus 0.9 ± 3.4, p = 0.002). There were no significant between-group differences in change for LV GLS, ejection fraction and volume. In patients with ACS and T2D, addition of empagliflozin to ACS therapy at discharge was associated with a reduction in LV mass and favourable changes in diastolic function parameters. Further studies are warranted to investigate these findings.