A Phase 3, Multicenter, Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Study Evaluating the Efficacy and Safety of Tirzepatide Once Weekly Compared to Placebo in Adult Participants With Type 1 Diabetes and Obesity or Overweight

Clinical Trial12 May 2026Phase 3

A Phase 3, Multicenter, Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Study Evaluating the Efficacy and Safety of Tirzepatide Once Weekly Compared to Placebo in Adult Participants With Type 1 Diabetes and Obesity or Overweight

Eli Lilly and Company

Phase 3 trial evaluating tirzepatide once weekly versus placebo in 905 adults with type 1 diabetes and obesity or overweight, measuring HbA1c change as primary endpoint. Double-blind, placebo-controlled study expected to complete November 2026, currently active but not recruiting. Eli Lilly is testing tirzepatide in type 1 diabetes, a population where GLP-1 agonists have limited evidence and where weight management remains an unmet need alongside glycemic control. This represents expansion into a new diabetes indication where insulin remains the cornerstone therapy.

Strategic Signal

Eli Lilly is pioneering GLP-1 use in type 1 diabetes, where endocrinologists have been cautious about GLP-1 agonist use given theoretical DKA risk concerns. FDA approval would create a new treatment paradigm for the estimated 1.6 million US adults with type 1 diabetes who struggle with weight gain from intensive insulin therapy. Success could trigger competitor trials in type 1 diabetes, though Novo Nordisk's semaglutide and Eli Lilly's own tirzepatide would face the challenge of demonstrating safety in insulin-dependent patients.

GLP-1Type 1 diabetesWeight lossEli Lilly

Original Abstract

The main purpose of this study is to find out how well and how safely tirzepatide works in adults who have type 1 diabetes and obesity or overweight. Participation in the study will last about 49 weeks. | Condition(s): Type 1 Diabetes; Obesity; Overweight | Primary endpoint(s): Change from Baseline in Hemoglobin A1c (HbA1c) | Enrollment: 905 (estimated) | Phase: Phase 3 | Sponsor: Eli Lilly and Company | Expected completion: 2026-11 | Status: Active Not Recruiting | Last update: 2026-05-12

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