A Clinical Trial Using Tirzepatide to Help Adults With Type 1 Diabetes Automatically Control Their Blood Sugar

Official title

Fully Closed-Loop Glucose Control in Adults With Type 1 Diabetes Using Tirzepatide: a Randomized, Multi-center, Open-label, Non-inferiority, Parallel Trial

Overview

This research study is testing whether a weekly medication called tirzepatide can help adults with type 1 diabetes use their insulin pump more easily, specifically by reducing or eliminating the need to count carbohydrates at meals. People with type 1 diabetes must take insulin for life, and even with advanced insulin pumps and continuous glucose monitors, many still struggle to keep blood sugar within the target range. One of the biggest challenges is carbohydrate counting, which requires estimating the amount of carbohydrates in every meal to give the correct insulin dose. Tirzepatide is a medication currently approved for type 2 diabetes and weight management. Early research suggests it may also help people with type 1 diabetes by lowering appetite, slowing digestion, reducing insulin needs, and smoothing after-meal blood sugar rises. This study will include 105 adults with type 1 diabetes at centers in Canada and Switzerland. Everyone will use the Tandem Control-IQ insulin pump with a Dexcom G7 continuous glucose monitor. Participants are randomly assigned to one of two groups: Tirzepatide group: Participants receive weekly tirzepatide injections. After the dose is gradually increased over 12 weeks, they will eventually try using their insulin pump without entering carbohydrate amounts at meals. Control group: Participants continue their usual therapy and keep counting carbohydrates for their mealtime insulin doses. The main goal of the study is to learn whether people taking tirzepatide can safely maintain good blood sugar control without counting carbs, compared with standard care. All participants will attend several clinic visits and share their glucose, insulin, and health data throughout the 32-week trial. Some centers will also conduct heart/fitness, or body-composition tests. As with any medication, tirzepatide may cause side effects such as nausea, vomiting, diarrhea, or decreased appetite. Rare but serious risks like gallbladder disease or pancreatitis are also monitored. Pregnancy must be avoided during the trial. Overall, this study aims to understand whether adding tirzepatide to automated insulin delivery can simplify diabetes management, reduce burden, and maintain safe and effective glucose control for adults living with type 1 diabetes.

Detailed description

Current diabetes technology, including hybrid automated insulin delivery systems like the Tandem Control-IQ paired with the Dexcom G7 continuous glucose monitor, improves glucose control but still relies heavily on patients entering carbohydrate amounts before eating, a task that is difficult, error-prone, and often stressful.

Tirzepatide, which is approved for type 2 diabetes and weight management, works by slowing digestion, lowering appetite, reducing insulin requirements, and improving after-meal glucose spikes, and early evidence suggests it may offer similar benefits in type 1 diabetes. This study is designed to determine whether adding once-weekly tirzepatide injections to a commercially available automated insulin delivery system can make diabetes management easier for adults with type 1, particularly by reducing or eliminating the need to count carbohydrates at meals.

In this 32-week trial, 105 adults will be randomly assigned to receive tirzepatide or no tirzepatide while all participants use the Control-IQ system. Those receiving tirzepatide will gradually increase their dose over 12 weeks, continue counting carbohydrates until week 26, and then stop announcing meals entirely for the final 6 weeks, while the control group will count carbohydrates throughout.

Across the study, participants will attend scheduled clinic visits, complete remote follow-ups, undergo laboratory tests, and, depending on the site, may complete heart function tests, body-composition scans, fitness testing, or gastric emptying assessments. Researchers will compare glucose control, insulin needs, weight, metabolic markers, meal patterns, and patient-reported outcomes between groups, with the primary goal of determining whether glucose management without carbohydrate counting is not worse than (non-inferior to) standard carbohydrate counting.

The study also closely monitors safety, as tirzepatide can cause nausea, vomiting, diarrhea, decreased appetite, and rare complications such as gallbladder disease or pancreatitis. Overall, this research aims to learn whether combining tirzepatide with automated insulin delivery can safely simplify diabetes management, reduce treatment burden, and improve metabolic outcomes for adults living with type 1 diabetes.

Interventions

• Drug Tirzepatide
  Tirzepatide, administered as a once-weekly subcutaneous injection, initiated at 2.5 mg and escalated in 2.5-mg increments every 4 weeks to a target of 10 mg or the maximally tolerated dose, used as an adjunct therapy in adults with type 1 diabetes using the Tandem Control-IQ automated insulin delivery system.
• Device Tandem Control-IQ Automated Insulin Delivery System (with Dexcom G7 CGM)
  This intervention uses the Tandem t:slim X2 insulin pump with the Control-IQ automated insulin delivery algorithm, integrated with the Dexcom G7 continuous glucose monitor. The system adjusts basal insulin and delivers automated correction boluses based on real-time glucose values. All participants receive standardized training and use this system for the full 32-week study. Rapid-acting insulin compatible with Control-IQ is required. This intervention is distinguished by its use under two diffe
• Behavioral Carbohydrate Counting
  Participants enter the estimated carbohydrate amount for every meal and snack into the Tandem Control-IQ insulin pump to calculate and deliver prandial insulin boluses. This reflects standard use of hybrid closed-loop systems. The procedure is maintained for the entire 32-week study in the control arm and during Weeks 1-26 in the tirzepatide arm.
• Behavioral No Meal Announcement
  Participants do not enter carbohydrate amounts or announce meals to the Tandem Control-IQ system. The pump operates without user-initiated prandial boluses, relying solely on automated basal adjustments and automated correction boluses. This intervention is implemented only in the tirzepatide arm during Weeks 27-32.

Primary outcome measures

• Daytime Time-in-Range [Time frame: During the final 6 weeks of the study]

Secondary outcome measures (12)

• Weight [Time frame: At enrollment, Week 8, Week 16, Week 24, and Week 32, At Week 8 and Week 16 post-study]
• Height [Time frame: At enrollment, Week 8, Week 16, Week 24, and Week 32, At Week 8 and Week 16 post-study.]
• Body Mass Index [Time frame: At enrollment, Week 8, Week 16, Week 24, and Week 32, At Week 8 and Week 16 post-study]
• Waist circumference [Time frame: At enrollment, Week 8, Week 16, Week 24, and Week 32, At Week 8 and Week 16 post-study]
• Waist-to-Hip Ratio [Time frame: At enrollment, Week 8, Week 16, Week 24, and Week 32, At Week 8 and Week 16 post-study.]
• Systolic Blood Pressure [Time frame: At enrollment, Week 8, Week 16, Week 24, and Week 32, At Week 8 and Week 16 post-study.]
• Diastolic Blood Pressure [Time frame: At enrollment, Week 8, Week 16, Week 24, and Week 32, At Week 8 and Week 16 post-study.]
• Resting Heart Rate [Time frame: At enrollment, Week 8, Week 16, Week 24, and Week 32, At Week 8 and Week 16 post-study.]
• Insulin-related measures [Time frame: Continuously from randomization through Week 32, with primary analysis focused on Weeks 27-32, At Week 8 and Week 16 post-study.]
• Glucose outcomes [Time frame: Continuously collected from randomization through Week 32, with key comparisons during Weeks 23-26 and Weeks 27-32, At Week 8 and Week 16 post-study.]
• Glycated Hemoglobin (HbA1c) [Time frame: At enrollment, mid-study at Week 16, and at the end-of-study visit at Week 32, At Week 8 and Week 16 post-study.]
• Estimated Glomerular Filtration Rate [Time frame: At enrollment, Week 16, and Week 32, At Week 8 and Week 16 post-study.]

Eligibility criteria

Inclusion criteria

• Age ≥ 18 years.
• Clinical diagnosis of type 1 diabetes for ≥ 1 year, per investigator judgment (confirmatory C-peptide and autoantibodies not required).
• A BMI ≥ 27 kg/m2.
• HbA1c > 6.5%, and < 12%.
• Current therapy: multiple daily injections or insulin pump.
• Willingness to use Tandem Control IQ insulin pump system with the use of rapid or ultra rapid-acting insulins compatible with Tandem Control-IQ pump (e.g. Fiasp is not compatible)
• Active carbohydrate counting for prandial insulin dosing.
• Individuals of childbearing potential must be using or agree to use an effective birth-control method. Childbearing potential refers to participants of the female sex post-menarche who have not reached menopause and who do not have a medical condition causing sterility (e.g., hysterectomy). Post-menopausal state refers to the absence of menses for 12 months without any alternative cause.

Exclusion criteria

• Use of GLP1-RAs within the last four weeks.
• Use of antihyperglycemic agents other than insulin or metformin within the last 2 weeks.
• Planned or ongoing pregnancy.
• Breastfeeding.
• Severe hypoglycemia requiring hospitalization in the past 2 months. Severe hypoglycemia is defined as requiring the assistance of another person, due to altered consciousness, to administer carbohydrates, glucagon, or other resuscitative actions.
• Diabetic ketoacidosis within the last 2 months.
• History of acute or chronic pancreatitis.
• Personal or family history of medullary thyroid cancer or multiple endocrine neoplasia type 2.
• Severe renal impairment with eGFR <30 mL/min/1.73 m2 (CKD-EPI), measured within the last four months.
• Clinically significant proliferative diabetic retinopathy or gastroparesis, as per the judgment of the investigator.
• Current or ≤ 1 month use of supraphysiological doses of oral or intravenous glucocorticoids.
• History of bariatric surgery within the last 6 months.
• Medical or psychiatric illness likely to interfere with participation (e.g. cirrhosis, active cancer, decompensated schizophrenia), per investigator judgment.
• Inability or unwillingness to comply with safe diabetes management practices, in the view of the investigator.
• Any safety concern that, in the investigator's judgment, precludes participation.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Open label

Primary purpose

Treatment

Study locations

Canada · 3 centers

• Institut de Recherches Cliniques de Montréal — Montreal
• McGill University Health Centre — Montreal
• Hygea Medical Clinic — Montreal

Switzerland · 1 center

• Insel Hospital, University Hospital Bern — Bern

Publications

• Marso SP, Bain SC, Consoli A, Eliaschewitz FG, Jodar E, Leiter LA, Lingvay I, Rosenstock J, Seufert J, Warren ML, Woo V, Hansen O, Holst AG, Pettersson J, Vilsboll T; SUSTAIN-6 Investigators. Semaglutide and Cardiovascular Outcomes in Patients with Type 2 Diabetes. N Engl J Med. 2016 Nov 10;375(19):1834-1844. doi: 10.1056/NEJMoa1607141. Epub 2016 Sep 15. PMID 27633186
• Karlsson J, Persson LO, Sjostrom L, Sullivan M. Psychometric properties and factor structure of the Three-Factor Eating Questionnaire (TFEQ) in obese men and women. Results from the Swedish Obese Subjects (SOS) study. Int J Obes Relat Metab Disord. 2000 Dec;24(12):1715-25. doi: 10.1038/sj.ijo.0801442. PMID 11126230
• Saisho Y. Use of Diabetes Treatment Satisfaction Questionnaire in Diabetes Care: Importance of Patient-Reported Outcomes. Int J Environ Res Public Health. 2018 May 9;15(5):947. doi: 10.3390/ijerph15050947. PMID 29747423
• Gonder-Frederick LA, Schmidt KM, Vajda KA, Greear ML, Singh H, Shepard JA, Cox DJ. Psychometric properties of the hypoglycemia fear survey-ii for adults with type 1 diabetes. Diabetes Care. 2011 Apr;34(4):801-6. doi: 10.2337/dc10-1343. Epub 2011 Feb 23. PMID 21346182
• Fisher L, Hessler D, Polonsky W, Strycker L, Masharani U, Peters A. Diabetes distress in adults with type 1 diabetes: Prevalence, incidence and change over time. J Diabetes Complications. 2016 Aug;30(6):1123-8. doi: 10.1016/j.jdiacomp.2016.03.032. Epub 2016 Apr 4. PMID 27118163
• Frias JP, Davies MJ, Rosenstock J, Perez Manghi FC, Fernandez Lando L, Bergman BK, Liu B, Cui X, Brown K; SURPASS-2 Investigators. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes. N Engl J Med. 2021 Aug 5;385(6):503-515. doi: 10.1056/NEJMoa2107519. Epub 2021 Jun 25. PMID 34170647
• Martin C, Ravussin E, Sanchez-Delgado G, Nishiyama H, Li J, Urva S, et al. The effect of tirzepatide during weight loss on food intake, appetite, food preference and food craving in people with obesity. Can J Diabetes. 2023 Jul;47(7 Suppl):S199. doi:10.1016/j.jcjd.2023.10.370
• Snell-Bergeon JK, Kaur G, Renner D, Akturk HK, Beatson C, Garg SK. Effectiveness of Semaglutide and Tirzepatide in Overweight and Obese Adults with Type 1 Diabetes. Diabetes Technol Ther. 2025 Jan;27(1):1-9. doi: 10.1089/dia.2024.0328. Epub 2025 Jan 2. PMID 39745353

Identifiers

NCT: NCT07284511 · 2026-12143

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗