At baseline (T0), the patients included in the study showed the following mean characteristics: age 43.61 ± 13.28 years, diabetes duration 25.19 ± 14.08 years, HbA1c 7.83 ± 1.39% (with 10 patients having HbA1c ≤ 7%), BMI 24.86 ± 3.99 kg/m2, and TDI 36.78 ± 17.01 units. Before the introduction of the Minimed™ 780G system 14 patients were on MDI insulin therapy, 11 patients were using a non-automated insulin pump system (nAID) combining an insulin pump with either a CGM or a flash glucose monitoring (FGM) glucose sensor, and the other study participants were on a PLGS system or a hybrid closed-loop (HCL) system not providing automatic boluses (7 and 10 patients respectively). During the 12-month period of using the AHCL system no episodes of ketoacidosis or severe hypoglycemia were documented. At 12 months (A12mo), 15 patients had a GT set at 120 mg/dl, 12 patients at 110 mg/dl, and 12 patients at 100 mg/dl. Ten patients had a TIA set at 3 h, 2 patients at 2 h 45 min, 8 patients at 2 h 30 min, 2 patients at 2 h 15 min, and 17 patients at 2 h. All study participants consistently maintained a high usage percentage (%) of the SmartGuard function, which remained stable over the 12-month period in auto-mode (SmartGuard A: 95.02 ± 10.65%; SmartGuard A3mo: 95.47 ± 8.96%; SmartGuard A6mo: 96.02 ± 7.99%; SmartGuard A12mo: 92.94 ± 11.83%). Additionally, all participants consistently maintained over 70% use of CGM throughout the study. Remarkably, just 14 days after switching from manual mode (M) to auto-mode (A), significant improvements in CGM metrics were observed. Notably, there was a significant increase in TITR% (p < 0.0001) and TIR% (p < 0.00001). Moreover, there were significant reductions in TAR% (p < 0.0001), TBR% (p = 0.0034), CV% (p < 0.0001), mean glucose (mg/dl; p < 0.0001), and GMI% (p = 0.0004) (Figs. 1, 2). These improvements in TITR%, TIR%, TAR%, CV%, GMI%, and mean glucose were sustained and even enhanced at subsequent time points, namely A3mo, A6mo, and A12mo, compared to the initial manual mode (M) (Figs. 1, 2), without an increase in TBR% (even decreased at A12mo compared to M; p = 0.0383). Even at A12mo, there was a significant increase in TITR% (p = 0.0271), TIR% (p < 0.0001), GMI% (p = 0.0295), and mean glucose (mg/dl; p = 0.0192), along with a significant reduction in TAR% (p < 0.0001) compared to A (Figs. 1, 2). Additionally, at A12mo, a significant reduction in HbA1c% was observed compared to T0 (HbA1c 7.02 ± 0.73% at A12mo versus 7.83 ± 1.39% at T0, p = 0.0094) and A3mo (HbA1c 7.02 ± 0.73% at A12mo versus 7.22 ± 0.75% at A3mo, p = 0.0249) (Fig. 3). Moreover, 20 patients achieved a target HbA1c of ≤ 7% at A12mo. Just 14 days into auto-mode (A), patients had already met target metrics based on standardized CGM criteria for clinical care. Specifically, the metrics were TIR 72.80 ± 10.86%, with 27 (64.28%) patients achieving a TIR of ≥ 70%; TAR 25.83 ± 11.19%, with 24 (57.14%) patients achieving a TAR of ≤ 25%; TBR 1.40 ± 1.56%, with 40 (95.23%) patients achieving a TBR of ≤ 4%; GMI 6.97 ± 0.38%, with 22 (52.38%) patients achieving a GMI of ≤ 7%; and CV 30.74 ± 4.36%, with 38 (90.47%) patients achieving a CV of ≤ 36%. These commendable metrics-related results were sustained throughout the 12-month follow-up. Fourteen days after switching to auto-mode, the TITR was 44.83 ± 11.83%, and at A12mo, it increased to 49.52 ± 11.75%, aligning with recommendations from several authors [11,12,13] (with an approximate increase of 12% compared to M). By the end of the observational period (A12mo), the other recorded CGM values were TIR 77.27 ± 9.50% (with an approximate increase of 15% from M), TAR 21.25 ± 10.08% (with an approximate decrease of 14% from M), TBR 1.61 ± 1.96% (with an approximate decrease of 1.20% from M), GMI 6.80 ± 0.39% (with an approximate decrease of 0.41% from M), and CV 30.06 ± 4.50% (with an approximate decrease of 4% from M). Interestingly, if we excluded patients with TIA of 3 h plus TG of 120 mg/dl (n = 7 patients), the TITR rose to 51.92 ± 11.37% (associated with a TIR of 78.60 ± 9.16%, a TBR of 1.75 ± 2.04%, a TAR of 19.82 ± 9.89%, a CV of 30.35 ± 4.43%, and a GMI of 6.74 ± 0.39%) meeting the desired threshold proposed by Castañeda et al. [11]. Moreover, if we considered only patients with TIA set at 2 h plus GT set at 100 mg/dl (n = 7 patients), the TITR was 55.85 ± 14.78% (associated with a TIR of 82 ± 10%, a TBR of 2.28 ± 3.30%, a TAR of 15.71 ± 11.60%, a CV of 29.24 ± 5.27%, and a GMI of 6.57 ± 0.49%). There was no notable difference in TDI at the end of the follow-up period (A12mo) compared to both the initial T0 and the manual mode (M). Additionally, the average BMI remained consistent over the 12-month period compared to the baseline (T0).

When we investigated potential correlations between TITR at A and A12mo and other glycemic outcomes at A and A12mo, as well as between TITR at A and A12mo and baseline (T0) parameters such as age, HbA1c, TDI, BMI, and duration of diabetes, several associations emerged. At A, TITR% showed a negative correlation with baseline HbA1c% (p = 0.0029), A TAR% (p < 0.0001), A GMI% (p < 0.0001), and A mean glucose mg/dl (p < 0.0001). Conversely, it had a positive correlation with A TIR% (p < 0.0001). There was a positive correlation also with A TBR% (p = 0.0097); however, A TBR, as previously described, was less than 2%, and TBR54 was less than 0.5%. At A12mo, TITR% exhibited a negative correlation with both baseline HbA1c% (p = 0.0034) and A12mo HbA1c% (p = 0.0002), A12mo TAR% (p < 0.0001), A12mo GMI% (p < 0.0001), and A12mo mean glucose mg/dl (p < 0.0001). A12mo TITR% showed a positive correlation with A12mo TIR% (p < 0.0001). We also observed a positive correlation with A12mo TBR% (p = 0.0012); however, A12mo TBR was less than 2%, and A12mo TBR54 was less than 0.5%. No correlations were found between A TITR% (as well as A12mo TITR%) and age, TDI, BMI, and duration of diabetes (T0). When the study population was subdivided by sex, duration of diabetes (≥ 25 years versus < 25 years) and baseline glycemic control (HbA1c > 7.5% versus ≤ 7.5%), there was a significant improvement in TITR%, as well as in the other CGM parameters, in all subgroups at A12mo compared to M. The notable distinction was in TBR, which showed a statistically significant decrease only among subjects with HbA1c > 7.5% (p = 0.0112); conversely, there was no significant change in TBR% at A12mo compared to M among subjects with HbA1c ≤ 7.5%.

Raw data results at different time points. M manual mode, A first 14 days auto-mode, A3mo first 14 days after 3 months auto-mode, A6mo first 14 days after 6 months auto-mode, A12mo first 14 days after 12 months auto-mode. TIR time in range, TITR time in tight range, TBR time below range, TAR time above range, CV glycemic variability, GMI glucose management indicator

Results at different time points (M, A, A3mo, A6mo, A12mo): a TIR%, b TITR%, c TBR%, d TAR%, e CV%, f GMI%, g mean glucose (mg/dl). M manual mode, A first 14 days auto-mode, A3mo first 14 days after 3 months auto-mode, A6mo first 14 days after 6 months auto-mode, A12mo first 14 days after 12 months auto-mode. TIR time in range, TITR time in tight range, TBR time below range, TAR time above range, CV glycemic variability, GMI glucose management indicator

Comparisons of glycated hemoglobin (HbA1c)% at baseline (T0) and at different time points post-advanced hybrid closed loop (AHCL) initiation (A3mo, A6mo, A12mo). A3mo first 14 days after 3 months auto-mode, A6mo first 14 days after 6 months auto-mode, A12mo first 14 days after 12 months auto-mode