Dexcom Hybrid Closed Loop Insulin Pump Study in Type 1 Diabetes

NCT05059860 | Completed

• 1 other identifier: 299847
• Study Type: observational
• Target: 30
• Locations: 1 country
• Sites: 1

Brief Summary

Treatment of Type 1 diabetes requires daily insulin therapy given by either multiple daily injections or by continuous infusion via a pump. The insulin dose is calculated taking into consideration blood glucose levels, food intake and activity levels, aiming to avoid high and low readings. The Tandem t:slim X2™ insulin pump has recently become available in NHS Scotland and can link with the Dexcom G6 continuous glucose monitoring (CGM) system. The Tandem Control IQ hybrid closed loop system is made up of the Tandem insulin pump communicating wirelessly with the Dexcom G6 CGM. The algorithm within the pump then automatically controls the background (basal) insulin infusion rate. Manually delivered bolus insulin is still required for meals. This system is designed to finely tune insulin delivery and increase the amount of time that glucose is in the target range, reducing hypoglycaemia and hyperglycaemia. Insulin pumps are funded by NHS Scotland, but the Dexcom G6 continuous glucose monitoring system is not, so this hybrid closed loop system is not currently routinely available in NHS Scotland. The purpose of this study is to gain experience of this system and investigate how effective and acceptable the hybrid closed loop system is for people in Scotland. Participants will be provided with the Dexcom G6 CGM device to link to their current pump to create the hybrid closed loop system for the duration of the study. 30 people with Type 1 diabetes who have been using the Tandem pump for at least one month will be invited to participate. The study will include a screening visit, a 30 day run-in period, 52 week treatment period and 12 week follow-up period. Diabetes control will be measured using HbA1c and downloaded information from the hybrid closed loop system. Participants will also complete questionnaires and a reflective diary.

Conditions

Type 1 Diabetes Mellitus

Outcome Measures

Primary Outcomes (5)

• HbA1c

  Measurement of HbA1c

  Change from baseline to 20 days after initiation of the sensor, and at 4, 12, 26, 52 and 64 weeks after initiation of the Control-IQ hybrid closed loop system

• Severe hypoglycaemia

  Self reported severe hypoglycaemia

  Change from the 12 weeks before baseline measures to 20 days after initiation of the sensor, and at 4, 12, 26, 52 and 64 weeks after initiation of the Control-IQ hybrid closed loop system.

• Time in range

  Percentage of time glucose is in range (download of Dexcom results)

  Change from baseline to 4, 12, 26 and 52 weeks after initiation of the Control-IQ hybrid closed loop system

• Time in hypoglycaemia

  Percentage of time hypoglycaemic

  Change from baseline to 4, 12, 26 and 52 weeks after initiation of the Control-IQ hybrid closed loop system.

• Time Control IQ system not in use

  Time when the Control-IQ hybrid closed loop system is not in use

  From baseline to 4, 12, 26 and 52 weeks after initiation of the system.

Secondary Outcomes (4)

• Diabetes distress score

  Change from baseline to 4, 12, 26, 52 and 64 weeks after initiation of the Control-IQ hybrid closed loop system.

• Problem Areas In Diabetes questionnaire

  Change from baseline to 4, 12, 26, 52 and 64 weeks after initiation of the Control-IQ hybrid closed loop system.

• Patient experience diary

  Change from baseline to 4, 12, 26, 52 and 64 weeks after initiation of the Control-IQ hybrid closed loop system.

• Hospital Anxiety and Depression questionnaire

  Change from baseline to 4, 12, 26, 52 and 64 weeks after initiation of the Control-IQ hybrid closed loop system.

Other Outcomes (1)

• Gold Hypoglycaemia questionnaire

  Change from baseline to 4, 12, 26, 52 and 64 weeks after initiation of the Control-IQ hybrid closed loop system.

Interventions

Tandem Control IQ Hybrid Closed Loop Insulin Delivery System DEVICE

The Tandem Control IQ hybrid closed loop insulin delivery system is made up of an externally worn Tandem insulin pump which communicates wirelessly to the Dexcom G6 CGM worn as a patch on the skin. The CGM measures glucose levels transmitting them into the computer within the pump. The computer then calculates how much insulin is required then dose delivery completes the cycle. The Control-IQ™ advanced technology adjusts insulin delivery to avoid glycaemic excursions, while still allowing the user to manually bolus at mealtimes.

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

30 patients with Type 1 diabetes will be recruited in NHS Lothian

You may qualify if:

• Clinical diagnosis of Type 1 diabetes
• Established on the Tandem pump for at least 1 month, using novorapid or humalog insulin
• HbA1c 40-90 mmol/mol inclusive within the previous 30 days or taken at screening
• Total daily dose of insulin 10-100 units
• Willing to attend study visits and complete all study assessments
• Able to give informed consent

You may not qualify if:

• Pregnant or planning pregnancy
• Any disorder which, in the investigators' opinion might jeopardise the patient's safety or compliance with the protocol
• Life expectancy less than one year
• Severe renal impairment (eGFR \<30ml/min)
• Weight \<25kg
• Patients prescribed hydroxycarbamide

Sponsors & Collaborators

• NHS Lothian: lead
• DexCom, Inc.: collaborator

Study Sites (1)

Professor John McKnight

Edinburgh, Lothian, EH4 2XU, United Kingdom

Location

MeSH Terms

Conditions

Diabetes Mellitus, Type 1

Condition Hierarchy (Ancestors)

Diabetes Mellitus; Glucose Metabolism Disorders; Metabolic Diseases; Nutritional and Metabolic Diseases; Endocrine System Diseases; Autoimmune Diseases; Immune System Diseases

Study Officials

• John McKnight

  NHS Lothian

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: observational
• Observational Model: CASE CONTROL
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER GOV
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: September 8, 2021
• First Posted: September 28, 2021
• Study Start: June 9, 2023
• Primary Completion: May 23, 2025
• Study Completion: May 23, 2025
• Last Updated: September 18, 2025

Record last verified: 2025-09

Locations

GB (1)