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

Status

Recruiting

Phase

Phase 2/3

Enrollment

105 participants (estimated)

Sponsor

McGill University Health Centre/Research Institute of the McGill University Health Centre · Other

Design

Randomized · Open label (no masking)

Countries

2 countries

Canada, Switzerland

Start

19 May 2026

Primary completion

Jan 2028 (estimated)

Completion

Jan 2029 (estimated)

First posted

16 Dec 2025

Last update posted

27 May 2026

Conditions

Type 1 Diabetes · Type 1 Diabetes Mellitus · T1D · T1DM · T1DM - Type 1 Diabetes Mellitus

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.

• Experimental

  Tirzepatide group

  Participants randomized to this arm receive once-weekly subcutaneous tirzepatide in addition to use of the Tandem Control-IQ insulin pump and Dexcom G7 continuous glucose monitor. Tirzepatide is initiated at 2.5 mg weekly and increased by 2.5 mg every 4 weeks to a target dose of 10 mg weekly or the maximally tolerated dose. Dose escalation may be delayed or reduced if participants experience intolerable gastrointestinal symptoms. During Weeks 1-26, participants continue standard carbohydrate counting for all meals. Beginning in Week 27, participants stop entering carbohydrate amounts into the pump (no meal announcements) for six weeks while continuing tirzepatide at their maintenance dose. Throughout the intervention, participants undergo regular safety assessments, remote glucose data reviews, insulin-pump parameter adjustments as needed, and scheduled in-person visits to monitor metabolic, cardiovascular, and patient-reported outcomes.

• Active comparator

  Control group

  Participants randomized to the control arm use the Tandem Control-IQ automated insulin delivery system with the Dexcom G7 continuous glucose monitor, following standard-of-care diabetes management. They continue carbohydrate counting for all meals throughout the 32-week study and deliver prandial insulin boluses based on estimated carbohydrate intake, as is typical for users of hybrid closed-loop systems. No tirzepatide injections are administered. Participants receive the same device training, follow-up schedule, safety monitoring, glucose data reviews, and pump parameter adjustments as the tirzepatide arm. This arm serves as an active comparator, representing current standard therapy for type 1 diabetes with automated insulin delivery and meal announcements.

1. Daytime Time-in-Range

   Time frame · During the final 6 weeks of the study

   Registry description

   The primary outcome is the percentage of daytime hours (06:00-24:00) during which participants' glucose levels, measured by the Dexcom G7 continuous glucose monitor, fall within the target range of 3.9-10.0 mmol/L.