Type 1 Diabetes MellitusNCT05059860
Dexcom Hybrid Closed Loop Insulin Pump Study in Type 1 Diabetes
An observational study of Type 1 Diabetes Mellitus, run by NHS Lothian at 1 site in United Kingdom.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Type 1 Diabetes Mellitus
- Type of treatment
- Medical device
- How many people
- 30 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- 9 Jun 2023to 23 May 2025
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Adult, Older adult
Study population: 30 patients with Type 1 diabetes will be recruited in NHS Lothian
Who may be able to join
- 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
Who cannot join
- 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
Trial locations and contacts
1 site in 1 country.
United Kingdom1 site
Professor John McKnight
Edinburgh, Lothian, EH4 2XU
About this study
Official title: An Evaluation of the Tandem IQ Insulin Pump and DEXCOM G6 Continuous Glucose Monitoring Hybrid Closed Loop Insulin Delivery System (Control-IQ) on Patient Wellbeing and Diabetes Control in Adults With Type 1 Diabetes
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.
Read more
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.
Read the detailed description
In those without diabetes insulin is automatically secreted according to requirement. The background insulin secretion rate will vary depending on need, and is affected by many factors e.g. activity or stress levels. When a person eats the rise of glucose is sensed and insulin automatically secreted to keep the glucose within a narrow range.
People with Type 1 diabetes cannot make insulin to control their blood glucose. Insulin is therefore required as treatment. This is given subcutaneously by injection or using an infusion pump. Both background insulin is required and boluses of insulin given when carbohydrate is eaten.
It is difficult to accurately calculate and deliver the correct amount of insulin. More recently standard treatment involved giving one of two injections of long acting insulin and more frequent injections of fast acting insulin when carbohydrate is ingested. The dose of insulin is determined by measuring the ambient glucose level, knowing the amount of carbohydrate in any meal and predicting activity during the subsequent four or five hours.
Insulin pumps can be used to provide a pre-tuned variable background insulin infusion with manual intervention to deliver boluses of insulin with food.
In Scotland many people have now replaced finger prick glucose testing with flash glucose monitoring. This uses a small subcutaneous needle that senses subcutaneous glucose levels and, when scanned this sensor will provide a measure of subcutaneous glucose and information on the last 8 hours of glucose values (Flash Glucose monitoring). This system does not currently link to an insulin pump.
The Tandem insulin pump has recently become available in NHS Scotland for those already established on pump therapy.
The Dexcom G6 continuous glucose monitoring (CGM) system provides continuous glucose monitoring (without requiring any scanning by the patient) but is not currently funded within NHS Scotland, except for special circumstances. This system does communicate via bluetooth with the T-slim insulin pump.
The Tandem Control IQ insulin delivery system uses the link between the dexcom glucose sensor and pump to control the background insulin delivery and has been shown to work well in those studied. Patients still have to administer insulin when ingesting carbohydrate. This system is described as a hybrid closed loop system.
Problems that can potentially occur using this system include loss of communication between sensor and pump (bluetooth or wired connection), the algorithm not working or glucose readings out with the set ranges resulting in the automatic system turning off.
It is also unknown how acceptable the 'loss of control' is to a more general diabetes population as individuals with diabetes are used to making all the insulin dose decisions very frequently across each day. Confidence in these systems, both by patients and clinicians will be vital if these are to be introduced into more general use.
Therefore, the potential for these systems to have a major impact for people with diabetes is clear, but further understanding of the effectiveness and acceptability of such systems in the Scottish population is required.
The Investigator's aim is to investigate the effect of this system compared to current 'best practice' in Scotland, to gain experience in using this system and to investigate the acceptability of this system in the Scottish population.
- Conditions
- Type 1 Diabetes Mellitus
- Being tested
- Tandem Control IQ Hybrid Closed Loop Insulin Delivery System
- Medical subject headings
- Diabetes Mellitus, Type 1
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Tandem Control IQ Hybrid Closed Loop Insulin Delivery SystemDevice
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.
What is being measured
The primary outcome is the main question the study is designed to answer.
HbA1c
Measurement of HbA1c
Measured: 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
Measured: 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)
Measured: 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
Measured: 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
Measured: From baseline to 4, 12, 26 and 52 weeks after initiation of the system.
Secondary outcomes (4)
Diabetes distress score
Diabetes distress score. The Diabetes Distress Score yields a total diabetes distress scale score plus 4 sub scale scores, each addressing a different kind of distress. The score is the sum of the patient's responses to the appropriate items divided by the number of items in that scale. A mean question score of 3 or higher (moderate distress) as a level of distress is worthy of clinical attention.
Measured: 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
Problem Areas In Diabetes questionnaire. Each question has five possible answers with a value from 0 to 4, with 0 representing "no problem" and 4 "a serious problem".
The scores are added up and multiplied by 1.25, generating a total score between 0 - 100.
Patients scoring 40 or higher may be at the level of "emotional burnout" and warrant special attention.
PAID scores in these patients may drop 10-15 points in response to educational and medical interventions.
An extremely low score (0-10) combined with poor glycaemic control may be indicative for denial
Measured: Change from baseline to 4, 12, 26, 52 and 64 weeks after initiation of the Control-IQ hybrid closed loop system.
Patient experience diary
Patient written report of experience using hybrid closed loop system
Measured: 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
Hospital Anxiety and Depression questionnaire. Minimum score is 0, maximum score is 21. 0-7 = Normal, 8-10 = Borderline abnormal (borderline case), 11-21 = Abnormal (case)
Measured: Change from baseline to 4, 12, 26, 52 and 64 weeks after initiation of the Control-IQ hybrid closed loop system.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted28 Sep 2021
- Study start9 Jun 2023
- Primary completion23 May 2025
- Study completion23 May 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Type 1 Diabetes MellitusStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case-control
- Time perspective
- Prospective
- Enrolment
- 30 participants (actual)
Sponsor and investigators
- Lead sponsor
- NHS Lothian
- Sponsor type
- Other government
- Collaborators
- DexCom, Inc.
- Responsible party
- Sponsor
- Investigators
- John McKnight, Principal investigator, NHS Lothian
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05059860
- Sponsor's protocol ID
- 299847
- Status last verified
- Sep 2025
- First submitted
- 8 Sep 2021
- Last updated
- 18 Sep 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 18 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- An Evaluation of the Tandem IQ Insulin Pump and DEXCOM G6 Continuous Glucose Monitoring Hybrid Closed Loop Insulin Delivery System (Control-IQ) on Patient Wellbeing and Diabetes Control in Adults With Type 1 Diabetes
- ClinicalTrials.gov ID
- NCT05059860
- Acronym / sponsor ID
- 299847
- Conditions
- Type 1 Diabetes Mellitus
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 30 participants (actual)
- Lead sponsor
- NHS LothianOther government
- Collaborators
- DexCom, Inc.
- Study start
- 9 Jun 2023 (actual)
- Primary completion
- 23 May 2025 (actual)
- Study completion
- 23 May 2025 (actual)
- First posted
- 28 Sep 2021 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
In those without diabetes insulin is automatically secreted according to requirement. The background insulin secretion rate will vary depending on need, and is affected by many factors e.g. activity or stress levels. When a person eats the rise of glucose is sensed and insulin automatically secreted to keep the glucose within a narrow range.
People with Type 1 diabetes cannot make insulin to control their blood glucose. Insulin is therefore required as treatment. This is given subcutaneously by injection or using an infusion pump. Both background insulin is required and boluses of insulin given when carbohydrate is eaten.
It is difficult to accurately calculate and deliver the correct amount of insulin. More recently standard treatment involved giving one of two injections of long acting insulin and more frequent injections of fast acting insulin when carbohydrate is ingested. The dose of insulin is determined by measuring the ambient glucose level, knowing the amount of carbohydrate in any meal and predicting activity during the subsequent four or five hours.
Insulin pumps can be used to provide a pre-tuned variable background insulin infusion with manual intervention to deliver boluses of insulin with food.
In Scotland many people have now replaced finger prick glucose testing with flash glucose monitoring. This uses a small subcutaneous needle that senses subcutaneous glucose levels and, when scanned this sensor will provide a measure of subcutaneous glucose and information on the last 8 hours of glucose values (Flash Glucose monitoring). This system does not currently link to an insulin pump.
The Tandem insulin pump has recently become available in NHS Scotland for those already established on pump therapy.
The Dexcom G6 continuous glucose monitoring (CGM) system provides continuous glucose monitoring (without requiring any scanning by the patient) but is not currently funded within NHS Scotland, except for special circumstances. This system does communicate via bluetooth with the T-slim insulin pump.
The Tandem Control IQ insulin delivery system uses the link between the dexcom glucose sensor and pump to control the background insulin delivery and has been shown to work well in those studied. Patients still have to administer insulin when ingesting carbohydrate. This system is described as a hybrid closed loop system.
Problems that can potentially occur using this system include loss of communication between sensor and pump (bluetooth or wired connection), the algorithm not working or glucose readings out with the set ranges resulting in the automatic system turning off.
It is also unknown how acceptable the 'loss of control' is to a more general diabetes population as individuals with diabetes are used to making all the insulin dose decisions very frequently across each day. Confidence in these systems, both by patients and clinicians will be vital if these are to be introduced into more general use.
Therefore, the potential for these systems to have a major impact for people with diabetes is clear, but further understanding of the effectiveness and acceptability of such systems in the Scottish population is required.
The Investigator's aim is to investigate the effect of this system compared to current 'best practice' in Scotland, to gain experience in using this system and to investigate the acceptability of this system in the Scottish population.
Study design
- Observational model
- Case-control
- Time perspective
- Prospective
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Age groups
- Adult, Older adult
- Study population
- 30 patients with Type 1 diabetes will be recruited in NHS Lothian
Key inclusion criteria (6 listed)
- 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
Key exclusion criteria (6 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Tandem Control IQ Hybrid Closed Loop Insulin Delivery SystemThe 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. | Device | – |
Primary outcome
HbA1c
Time frame: 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
Measurement of HbA1c
Severe hypoglycaemia
Time frame: 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.
Self reported severe hypoglycaemia
Time in range
Time frame: Change from baseline to 4, 12, 26 and 52 weeks after initiation of the Control-IQ hybrid closed loop system
Percentage of time glucose is in range (download of Dexcom results)
Time in hypoglycaemia
Time frame: Change from baseline to 4, 12, 26 and 52 weeks after initiation of the Control-IQ hybrid closed loop system.
Percentage of time hypoglycaemic
Time Control IQ system not in use
Time frame: From baseline to 4, 12, 26 and 52 weeks after initiation of the system.
Time when the Control-IQ hybrid closed loop system is not in use
4 secondary outcomes
Diabetes distress score
Time frame: 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
Time frame: Change from baseline to 4, 12, 26, 52 and 64 weeks after initiation of the Control-IQ hybrid closed loop system.
Patient experience diary
Time frame: 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
Time frame: Change from baseline to 4, 12, 26, 52 and 64 weeks after initiation of the Control-IQ hybrid closed loop system.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 18 Sep 2025.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
John McKnight principal investigator
NHS Lothian
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Type 1 Diabetes Mellitus, run by NHS Lothian at 1 site in United Kingdom.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 18 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
HbA1c (time frame: 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). The study lists 5 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 18 Sep 2025.