The use by diabetes patients of real-time Continuous Glucose Monitoring (CGM) system is becoming widespread and has changed diabetic practice. Automated closed-loop (CL) insulin therapy has come of age. This major technological advance is expected to significantly improve the quality of care for adults, adolescents and children with type 1 diabetes.

Questions remain about patients' perception and acceptance on this automatisation of the management of their glycemic variability.

Thus this study is built to evaluate the impact of the activation of the closed-loop on quality of life and burden of their diabetes in patients with type 1 diabetes under CSII.

This cohort study will follow patients with type 1 diabetes undergoing under continuous subcutaneous insulin infusion (CSII) with Continuous Glucose Monitoring (GCM). After inclusion visit, there's a 20 days' period to assess their quality of life and perception of the burden of their diabetes and confirm their eligibility to the closer-loop. During this 20 days' period, patients should complete all the self-questionnaires.

Then, during the 2d visit, the closed-loop will be activated by the diabetologist for a 6 months follow-up including six visits with 3 phone contacts (at week 1, week 2 and week 6) then 2 direct visits at 3 months and 6 months.

The 3 phone contacts are mainly planned, as recommended in French guidelines, to ensure the good use of the device and to detect or prevent any unexpected events.

The 2 visits at 3 and 6 months, are planned to assess the glycemic variability using Continuous Glucose Monitoring data and to collect perception of the patients via the 2 main criteria self questionnaires (Quality of life and burden to be filled-in by patients at 3 and 6 months) and all perception dimensions by all the self questionnaires.

Main results will provide data on the evolution of quality of life and burden of diabetes by comparison between scores at 6 months and baseline, and evolution of glycemic variability.

Inclusion Criteria:

• Type 1 diabetic patients undergoing a CSII therapy for at least 6 months and using Tandem t:slim X2 for at least 4 weeks.
• Patient using CGM for 6 months including Dexcon G6 for at least 4 weeks.
• Eligible patient (according to French Society recommendations) for activation of the closed loop
• Informed Patient accepting the computer processing of their medical data.
• Patient correctly completing the 2 main self questionnaires
• Patient with HbA1c below 11%

Exclusion Criteria:

• Pregnancy or Lactation during the study
• Patient with a diabetic retinopathy not controlled by laser
• Patient suffering from a disease or undertaking a treatment altering glucose metabolism