Long-term Observation Of Patient Engagement in Automated Insulin Delivery (LOOPED)

The purpose of this study is to assess the long-term evolution of patient interaction with the CONTROL-IQ (Tandem™) hybrid closed-loop (HCL) system in individuals with type 1 diabetes over 24 months. Specifically, the study examines user-initiated boluses and carbohydrate announcements to determine whether initially low-engagement users increase their involvement over time or, conversely, whether highly engaged users gradually rely more on automation.

Study Overview

• Status: Completed
• Conditions: Type 1 Diabetes Mellitus
• Intervention / Treatment: Device: CONTROL-IQ (Tandem™)

Detailed Description

Automated insulin delivery (AID) systems have revolutionized type 1 diabetes (T1D) management, offering superior glycemic control and quality of life compared to sensor-augmented insulin pumps or multiple daily injections (MDI). However, current AID systems operate as hybrid closed-loop (HCL) systems, requiring user intervention for meal boluses, including carbohydrate counting and timely insulin administration.

Control-IQ (Tandem™) was the second AID system reimbursed by the French National Health Insurance and is now widely used in France. It combines the Tandem™ t:slim insulin pump with Dexcom™ G6 continuous glucose monitoring (CGM), adjusting basal insulin every five minutes based on glucose predictions and delivering automatic correction boluses once per hour. Despite these automation features, users must still manually initiate meal boluses, and additional correction boluses remain optional. While engagement in carbohydrate counting and timely meal announcements improves metabolic outcomes, real-world data suggest that AID benefits individuals across varying engagement levels.

Long-term data on patient behavior and engagement, particularly regarding carbohydrate announcements and the ratio of automatic to user-initiated boluses, remain limited. Understanding these patterns could reveal whether initially low-engagement users increase involvement over time or whether highly engaged users eventually rely more on automation.

This single-center, 24-month observational study will follow all T1D patients treated with Control-IQ at the Centre Hospitalier Sud-Francilien between October 2021 and October 2024.

• Study Type: Observational
• Enrollment (Actual): 453

Contacts and Locations

Study Locations

• France
  • Corbeil-essonnes Cedex, France, 91106
    • Centre Hospitalier Sud Francilien

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The population will be selected from the diabetes department of a French public hospital. All eligible patients will be included in the study.

Description

Inclusion Criteria:

• Patients using the CONTROL-IQ hybrid closed-loop system with data uploaded to the myDiabby platform at least once between October 2021 and October 2024, affiliated with the diabetology department of CHSF.

Exclusion Criteria:

• Patients with a type of diabetes other than type 1 diabetes.
• Patients who have objected to the use of their data.

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
With device	Device: CONTROL-IQ (Tandem™); interaction with the CONTROL-IQ (Tandem™) hybrid closed-loop (HCL) system in individuals with type 1 diabetes

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
number of automatic boluses	To assess the 24-month evolution of the automatic-to-user-initiated bolus ratio	repeated measurement over 24 months (8 quarters)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
time spent in closed-loop mode	Measurement of the quarterly evolution, over 24 months, of the percentage of time spent in closed-loop mode (CONTROL-IQ ON)	repeated measurement over 24 months (8 quarters)
insulin dose (UI)	Measurement of the quarterly evolution, over 24 months, of the average of total daily insulin dose (UI)	repeated measurement over 24 months (8 quarters)
carbohydrates	Measurement of the quarterly evolution, over 24 months, of the average amount of carbohydrates reported daily in closed-loop mode (CONTROL-IQ).	repeated measurement over 24 months (8 quarters)
glucose	Measurement of the quarterly evolution, over 24 months, of continuous glucose monitoring parameters, including average glucose in closed-loop mode (CONTROL-IQ).	Repeated measurement over 24 months (8 quarters)
glucose management indicator	Measurement of the quarterly evolution, over 24 months, of continuous glucose monitoring parameters, including average glucose management indicator in closed-loop mode (CONTROL-IQ).	Repeated measurement over 24 months (8 quarters)
glucose coefficient of variation	Measurement of the quarterly evolution, over 24 months, of continuous glucose monitoring parameters, including glucose coefficient of variation in closed-loop mode (CONTROL-IQ).	Repeated measurement over 24 months (8 quarters)
percentage of time in target range (70-180 mg/dL)	Measurement of the quarterly evolution, over 24 months, of continuous glucose monitoring parameters, including percentage of time in target range (70-180 mg/dL) in closed-loop mode (CONTROL-IQ).	Repeated measurement over 24 months (8 quarters)

Collaborators and Investigators

• Sponsor: Centre Hospitalier Sud Francilien
• Investigators: Principal Investigator: Coralie AMADOU, MD, Centre Hospitalier Sud Francilien

Study record dates

Study Major Dates

• Study Start (Actual): March 20, 2025
• Primary Completion (Actual): April 30, 2025
• Study Completion (Actual): April 30, 2025

Study Registration Dates

• First Submitted: February 21, 2025
• First Submitted That Met QC Criteria: February 27, 2025
• First Posted (Actual): March 5, 2025

Study Record Updates

• Last Update Posted (Actual): June 20, 2025
• Last Update Submitted That Met QC Criteria: June 17, 2025
• Last Verified: June 1, 2025

More Information

Terms related to this study

• Keywords: Continuous glucose monitoring; Type 1 diabetes mellitus; Automated insulin delivery; Carbohydrate counting; Meal announcement
• Additional Relevant MeSH Terms: Endocrine System Diseases; Metabolic Diseases; Autoimmune Diseases; Immune System Diseases; Glucose Metabolism Disorders; Diabetes Mellitus; Diabetes Mellitus, Type 1
• Other Study ID Numbers: 2025/0001

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No