Objective To investigate the effect of dapagliflozin on myocardial work and energy metabolism in patients with heart failure with reduced ejection fraction(HFrEF)without type 2 diabetes mellitus(T2DM).Methods Patients with HFrEF without T2DM who visited Wuzhou People's Hospital from January 2021 to January 2022 were randomly divided into conventional group and dapagliflozin group(conventional treatment+dapagliflozin).After treatment(12 months),myocardial work[global work index(GWI),global constructed work(GCW),global wasted work(GW),and global work efficiency(GWE)],energy metabolism[(free fatty acids(FFA)and β-hydroxybutyric acid(β-HB)],traditional cardiac function[left ventricular end-diastolic diameter(LVEDD),left ventricular end-systolic diameter(LVESD),and left ventricular ejection fraction(LVEF)],clinical efficacy,prognosis[mortality,rehospitalization,and incidence of major adverse cardiovascular events(MACE)]and adverse reactions were compared between the two groups.Results A total of 128 patients with HFrEF without T2DM were enrolled,including 63 patients in the dapagliflozin group and 65 patients in the conventional group.After treatment,the LVEDD,LVESD,GWW,NT-pro BNP in the dapagliflozin group was significantly lower than that in the conventional group(P＜0.05),while the LVEF,GWI,GCW,GWE,β-HB acid and FFA were significantly higher than those in the conventional group(P＜0.05).The total effective rate and hypoglycemia rates in the dapagliflozin group were significantly higher than those in the conventional group(P＜0.05),and the rehospitalization rate and MACE rate were significantly lower than those in the conventional group(P＜0.05).There were no significant differences in mortality,renal adverse events,urinary tract infections and gastrointestinal symptoms between the two groups(P＞0.05).Conclusion Dapagliflozin has significant clinical efficacy in patients with HFrEF without T2DM,which can increase the serum levels of FFA and ketones,improve effective work,and reduce ineffective work,but it is necessary to be vigilant against hypoglycemia.