We aimed to investigate the clinical factors affecting the therapeutic effectiveness of the sodium-glucose cotransporter-2 inhibitor empagliflozin in patients with type 2 diabetes mellitus (T2DM). We reviewed the medical records of 374 T2DM patients aged between 20 and 75 years who were prescribed empagliflozin 10 mg or 25 mg as add-on therapy for more than 90 consecutive days. Changes in hemoglobin A1c (HbA1c) from baseline levels and the reduction in body weights of the study participants were assessed. We found that younger patients (≤ 50 years), patients with the highest levels of HbA1c (>9%) at baseline, patients with an estimated glomerular filtration rate (eGFR) of >90 mL/min/1.73 m2, and patients with a shorter duration of T2DM (< 10 years) were more likely to exhibit a better glycemic response. Multivariate linear regression analysis revealed that a shorter duration of T2DM, higher baseline levels of HbA1c, and higher eGFR were positively associated with HbA1c reduction. Higher BMI and lower HbA1c levels were predictors of a more significant reduction in body weight among patients taking empagliflozin. The glucose-lowering effect of empagliflozin was more evident in T2DM patients with higher baseline HbA1c levels, better renal function, and shorter duration of T2DM.