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Aim: To evaluate the long-term efficacy, up to 2 years, of an advanced hybrid closed-loop (AHCL) system and to assess predictors of best results of the therapy. Methods: We retrospectively evaluated 296 adults with type 1 diabetes mellitus [mean age 42.8 ± 16.5 years, men 42.9%, duration of diabetes 22.5 ± 12.8 years, body mass index 24.9 ± 4.7 kg/m 2 , baseline glycated hemoglobin (HbA 1c ) 63.4 ± 12.2 mmol/mol (8.0 ± 1.1%) ] who used the MiniMed™ 780G system. Demographic and clinical data were recorded. Continuous glucose monitoring (CGM)-derived metrics and insulin requirement were analyzed from the 4 weeks before and from every quarter after the switch to the AHCL system. Results: In the first quarter of AHCL treatment, all CGM metrics improved. Time in range (TIR) increased from 58.1 ± 17.5% to 70.3 ± 9.5% ( P  < 0.0001). The improvement lasted for up to 2 years of observation regardless of previous insulin therapies. Throughout the period of observation, 53.4% of participants achieved mean TIR >70%, 92.6% mean time below range <4%, and 46% mean glucose management indicator <53 mmol/mol (7.0%). At univariable logistic regression older age, lower baseline HbA 1c and insulin requirement were associated with mean TIR >70%. At multivariable analysis, lower HbA 1c remained independently associated with a better glycemic control. However, mean TIR increased more in participants with a higher baseline HbA 1c . Conclusions: Switching to an AHCL leads to a rapid improvement in glycemic control lasting for up to 24 months along with a low risk for hypoglycemia, confirming the safety of the system. Lower baseline HbA 1c was the main predictor of better efficacy of therapy, although higher baseline HbA 1c was associated with the greatest improvement in mean TIR.

There are no data whether hybrid closed-loop (HCL) systems are superior to sensor-augmented pump (SAP) therapy with predictive low glucose suspend (PLGS) feature in improving glucose control. Aim of our study was to evaluate the effect on metabolic control and glucose variability of the switch from SAP therapy with PLGS to a HCL system in type 1 diabetic individuals. Forty adults with type 1 diabetes, who had been using SAP therapy with PLGS feature (Minimed 640G; Medtronic, Northridge, CA) for at least 12 months were evaluated in a 6-month case-control observational retrospective study. Twenty subjects who consecutively switched from Minimed 640G to a HCL system (Minimed 670G; Medtronic) (670G group) were compared with a control group consisting of 20 subjects who continued with the MiniMed 640G pump (640G group) matched for age, gender, and HbA 1c . At the end of the study there was a significant reduction in average HbA 1c levels (-4.9 ± 6.4 mmol/mol [-0.4% ± 0.6%], P  < 0.01), sensor glucose concentrations (-15.4 ± 17.7 mg/dL, P  < 0.005), coefficient of variation of sensor glucose concentrations (-3.8% ± 3.6%, P  < 0.01), percentage time spent in both hyperglycemic range 181-250 mg/dL (-5.1% ± 4.5%, P  < 0.05), and >250 mg/dL (-6.1% ± 6.9%, P  < 0.05) in the 670G group, whereas they remained unchanged in the 640G group. Percentage of time spent in euglycemic range significantly increased (11.6% ± 8.3%, P  < 0.005) only in the 670G group. There was no change in time spent in hypoglycemic range in both groups. In adults with type 1 diabetes, switching from a 640G to a 670G system significantly improved glucose control and reduced glucose variability, thus reaching in most cases the recommended targets for time spent in euglycemic and hyperglycemic ranges without increasing the risk of hypoglycemia.