Main characteristics of the included trials.

Background
Longer outpatient studies have demonstrated that hybrid closed loop (HCL) use has led to a concomitant reduction in glycated hemoglobin(HbA1c) by 0.3%–0.7%. However, reports have also indicated that HbA1c levels are not declined in the long-term use of HCL. Therefore, we wonder that 3 months use of HCL could improve glycated hemoglobin levels in adolescents and children with T1D.
Methods
Relevant studies were searched electronically in the Cochrane Library, PubMed, and Embase utilizing the key words “Pediatrics or Child or Adolescent”, “Insulin Infusion Systems” and “Diabetes Mellitus” from inception to 17th March 2024 to evaluate the performance of HCL on HbA1c in adolescents, and children with T1D.
Results
Nine studies involving 927 patients were identified. Three months use of HCL show a beneficial effect on HbA1c management (p <0.001) as compared to standard of care in adolescents and children with T1D, without evidence of heterogeneity between articles (I2 = 40%, p = 0.10). HCL did significantly increase the overall average percentage of hypoglycemic time between 70 and 180 mg/dL (TIR) (p <0.001; I2 = 51%). HCL did not show a beneficial effect on hypoglycemic time <70 mg/dL and <54 mg/dL (p >0.05). The overall percentage of hyperglycemic time was significantly decreased in HCL group compared to the control group when it was defined as >180 mg/dL (p <0.001; I2 = 83%), >250 mg/dL (p = 0.007, I2 = 86%) and >300 mg/dL (p = 0.005; I2 = 76%). The mean glucose level was significantly decreased by HCL (p <0.001; I2 = 58%), however, no significant difference was found in coefficient of variation of sensor glucose (p = 0.82; I2 = 71%) and daily insulin dose (p = 0.94; I2 <0.001) between the HCL group and the control group.
Conclusions
HCL had a beneficial effect on HbA1c management and TIR without increased hypoglycemic time as compared to standard of care in adolescents and children with T1D when therapy duration of HCL was not less than three months.
Trial number and registry URL
CRD42022367493; https://www.crd.york.ac.uk/PROSPERO, Principal investigator: Zhen-feng Zhou, Date of registration: October 30, 2022.