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Phase 2RecruitingNCT06820281

TIRTLE2: acute metabolic effects of tirzepatide in T1D

What this study tests

Recruiting Australian Phase 2 double-blinded placebo-controlled mechanistic clamp study of six weeks of weekly 2.5 mg tirzepatide versus saline placebo in adults with T1D on AID, per registry. It extends TIRTLE1, is not a glycemic-outcome pivotal, and tirzepatide is not approved for T1D.

Editorial review: .

Registry checked: 2026-09-17. Registry’s own update: 2026-09-16.

Most recent recorded citation date: 2026-09-16. Only explicit date metadata is included; an undated citation may be newer. This does not mean every claim was reviewed on that date.

Trial status, labels and access can change between reviews. How we review the evidence · How to read the evidence

Full sources ↓Full discussion ↓Report an issue →

Evidence at a glance

Who can enter the study?
Adults 18–70 with T1D for at least two years, BMI at least 25 kg/m2, HbA1c 9.0% or lower, using automated insulin delivery. Recent GLP-1/GIP agonists, hypoglycemia unawareness, and eGFR below 60 mL/min/1.73 m2 are excluded. Registered eligibility ↗Enrollment criteria describe who may enter. They do not establish who was analyzed or the denominator for a reported result.
Reported benefit and results
No results posted in the registry. Recruiting; estimated n=44; actual start 7 July 2026; estimated primary completion 31 December 2027. Last registry update 16 September 2026; checked 17 September 2026.Read the result sources and their limitations →
Important harms
Read the reported results, safety discussion and original sources. A separate harms summary is not available; this does not establish safety.
Research access and approval
Study regions: Australia. A trial listing does not establish product approval or current recruitment at a particular site. Check the study’s current entry requirements.
What remains uncertain?
Read the full discussion and original sources for study limitations. Planned endpoints and completion dates are not results.

Research status alone does not establish approval, clinical benefit or local availability.

Australian sites in the registry

  • Victor Chang Cardiac Research Institute, Sydney, New South Wales — Recruiting

Overall recruitment does not imply availability at every site. Confirm eligibility and local recruitment with the study team.

Primary endpoints

  • Change from baseline in whole-body insulin sensitivity on a hyperinsulinemic-euglycemic clamp at 6 weeks, per registry

The full picture

TIRTLE2 asks whether a low, short course of tirzepatide changes insulin sensitivity and glucagon responses in T1D before much weight is lost. It does not replace TIRTLE1, and it does not make tirzepatide a T1D treatment. Glucose units in the protocol: time in range 70–180 mg/dL (3.9–10.0 mmol/L); level-2 hypoglycemia below 54 mg/dL (3.0 mmol/L).

Sources

  1. [1]