Objective:To investigate the clinical efficacy of daggliflozin in the treatment of type 2 diabetes mellitus complicated by coronary heart disease and cardiac insufficiency.Methods:Seventy patients with type 2 diabetes mellitus complicated by coronary heart disease and cardiac insufficiency who received treatment in The Second People's Hospital of Liaocheng, The Second Hospital of Liaocheng Affiliated to Shandong First Medical University from March 2021 to February 2022 were included in this study. They were randomly divided into a control group ( n = 35) and an observation group ( n = 35). Based on conventional treatment, the control group was treated with metformin, while the observation group was treated with daggliflozin. Both groups were treated for 6 months. Pre- and post-treatment blood glucose and cardiac function as well as adverse reactions and prognosis were compared between the two groups. Results:After treatment, fasting blood glucose, 2-hour post-prandial glucose, glycosylated hemoglobin, fasting insulin, 2-hour post-prandial insulin level, left ventricular end-diastolic diameter, and peripheral blood N-terminal B-type natriuretic peptide levels in the observation group were (6.69 ± 1.83) mmol/L, (9.30 ± 2.96) mmol/L, (7.50 ± 0.98)%, (9.23 ± 2.80) mIU/L, (55.36 ± 8.38) mIU/L, (52.06 ± 5.39) mm, and (5.02 ± 1.98) μg/L, respectively, and they were (7.68 ± 2.03) mmol/L, (10.98 ± 3.33) mmol/L, (8.09 ± 1.25)%, (10.60 ± 2.26) mIU/L, (60.26 ± 8.98) mIU/L, (55.06 ± 5.86) mm, and (6.16 ± 2.28) μg/L, respectively, in the control group. There were significant differences in these indexes between the two groups ( t = 2.14, 2.23, 2.19, 2.25, 2.36, 2.22, 2.23, all P < 0.05). The left ventricular ejection fraction and 6-minute walking test in the observation group were (40.06 ± 5.26)% and (370.69 ± 52.26) m, which were significantly higher than (37.35 ± 4.33)% and (343.98 ± 38.69) m in the control group ( t = 2.35, 2.43, both P < 0.05). During the treatment period, there were no deaths in either group. Conclusion:Daggliflozin combined with conventional treatment can greatly improve glycemic control in patients with diabetes mellitus complicated by coronary heart disease and cardiac insufficiency. The combined therapy contributes to the improvement in cardiac function and is therefore worthy of promotion.