Researchers in Canada are launching a groundbreaking clinical trial to test whether tirzepatide, a medication commonly used for type 2 diabetes, can help people with type 1 diabetes achieve fully automated blood sugar control without manually counting carbohydrates or announcing meals. The three-year study, led by Drs. Ahmad Haidar and Melissa-Rosina Pasqua at McGill University and funded by Breakthrough T1D, will enroll 105 adults using the Tandem Control-IQ automated insulin delivery system.

What Is the Current Challenge With Automated Insulin Systems?

Today's automated insulin delivery (AID) systems, also called hybrid closed-loop systems, combine an insulin pump with a continuous glucose monitor (CGM) that work together through an algorithm to automatically adjust insulin doses based on blood sugar levels. However, most systems still require users to manually count carbohydrates and deliver insulin boluses (extra doses) before meals.

This manual step exists because of a timing mismatch: glucose from food enters the bloodstream quickly, but insulin delivered under the skin acts more slowly. Without a meal announcement, the system cannot deliver insulin fast enough to prevent post-meal blood sugar spikes. The trial aims to overcome this limitation by using tirzepatide to bridge the gap between food absorption and insulin action.

How Could Tirzepatide Enable Fully Closed-Loop Insulin Delivery?

Tirzepatide is a glucagon-like peptide-1 receptor agonist (GLP-1RA), a class of medication that works by helping the pancreas respond better to hormonal signals released after eating. Currently approved by Health Canada for type 2 diabetes (under the brand name Mounjaro) and weight management (Zepbound), tirzepatide addresses the timing mismatch through three key mechanisms:

• Slows gastric emptying: Delays how quickly glucose from food enters the bloodstream, giving insulin more time to work.
• Suppresses glucagon: Reduces the hormone that raises blood glucose, helping prevent post-meal spikes without manual intervention.
• Reduces appetite: Lowers food intake and daily insulin requirements, making blood sugar easier to manage automatically.

Together, these effects may allow an automated system to maintain stable glucose levels without requiring users to announce meals or count carbohydrates, potentially moving toward truly closed-loop insulin delivery.

What Will the Trial Actually Test?

The study, titled "A Clinical Trial Using Tirzepatide to Help Adults with Type 1 Diabetes Automatically Control Their Blood Sugar," is estimated to run in Montreal from 2026 to 2029. All 105 participants will initially use the Tandem Control-IQ pump in hybrid mode, which still requires manual meal boluses. In the final weeks of the study, participants taking tirzepatide will switch to fully automated mode, where the system manages insulin delivery without these manual meal announcements.

The trial is being conducted in collaboration with the Institut de recherches cliniques de Montréal and the University of Bern, bringing together expertise from multiple institutions to evaluate whether this approach works in real-world conditions.

Steps to Understanding Your Diabetes Management Options

• Talk to your doctor about CGM technology: Continuous glucose monitors provide real-time data about how your body responds to food and activity, helping you and your care team understand your unique metabolism.
• Ask about adjunctive therapies: Recent clinical practice guidelines from Diabetes Canada recommend that adjunctive therapies, like GLP-1RAs, may be considered for adults with type 1 diabetes based on shared decision-making with your healthcare provider.
• Explore automated insulin delivery systems: Updated guidelines recommend that insulin be delivered ideally by an insulin pump integrated with a CGM in an AID system, and these devices should be offered to all individuals with type 1 diabetes who are willing to wear and operate them.

Why Does This Matter for People With Type 1 Diabetes?

Managing type 1 diabetes requires constant vigilance and manual intervention. The burden of carbohydrate counting and meal announcements is one of the most challenging aspects of daily diabetes care. If tirzepatide can reduce or eliminate this requirement, it could significantly improve quality of life for people with type 1 diabetes by reducing the cognitive and physical demands of managing their condition.

It is important to note that tirzepatide is not currently approved by Health Canada for use in type 1 diabetes; this trial will help determine whether it is safe and effective for this population. The research builds on growing evidence that medications originally developed for type 2 diabetes may offer benefits for people with type 1 diabetes when used alongside insulin therapy.

For people interested in participating in diabetes clinical trials, Breakthrough T1D maintains a registry of ongoing studies. The results of this tirzepatide trial could reshape how automated insulin systems are designed and used in the coming years, potentially moving the field closer to truly hands-free blood sugar management.