Introduction and aims: Advances in glucose monitoring and insulin pump therapy has allowed the development of increasingly sophisticated systems that provide automated insulin delivery (AID), leading to significant improvement of daily self-management and quality of life of people with diabetes. We retrospectively evaluated the efficacy of AID in patients on MDI (multiple daily injection), CSII (continuous subcutaneous insulin infusion) or SAP (sensor augmented pump) therapy. Methods: We analysed 121 insulin treated subjects [45 men and 73 women, median age 46 years (34-55), diabetes duration 24 years (17-37) and HbA1c value 57 mmol/mol (49-75)] of whom 31 (26%) were on MDI, 29 (24%) on CSII and 61 (50%) on SAP. Due to inadequate glycaemic control, between 2021 and 2023 patients started AID therapy (22% Diabeloop closed-loop system, 35% SmartGuard and 43% Tandem Control IQ). Patients were evaluated at baseline and at 0.5, 6 and 12 months after AID application by assessing HbA1c, CMG parameters (including TIR and GMI) and the glycaemic risk index (GRI). Results: Glycemic control improved rapidly and significantly after AID, with significantly (p<0.05) better TIR and GRI at the 0.5-month control, which persisted during the follow-up. These effects were more marked in the MDI group, in which patients had higher HbA1c (60±14 mmol/mol), lower TIR (52±17%) and higher GRI (56±5%) pre-AID than those in the SAP group (55±7 mmol/mol, 64±15% and 44±22%) (all p<0.05 after the ANOVA test with the Bonferroni correction). At the last control, the MDI, CSII and SAP group showed superimposable glucose control (HbA1c: 48±10, 51±5 and 47±7 mmol/mol; TIR: 72±14, 75±7 and 76±13%; GRI: 35±15, 27±9 and 26±12%; GMI: 6.8±0.2, 6.9±0.2 and 6.6±0.5%). No difference was observed as for the three different AID therapy systems. Conclusions: This study confirms the higher efficacy of AID systems on glycaemic control compared to MDI, CSII and SAP, as proven by the rapid and persistent improvement of all the parameters considered. The different AID systems used in this study showed similar efficacy.