A Master Protocol to Investigate the Efficacy and Safety of LY3437943 Once Weekly in Participants With Type 2 Diabetes Mellitus Who Have Obesity or Overweight: A Randomized Double-Blind, Placebo-Controlled Trial

ClinicalTrials13 Apr 2026·Phase 3● 8/10i

A Master Protocol to Investigate the Efficacy and Safety of LY3437943 Once Weekly in Participants With Type 2 Diabetes Mellitus Who Have Obesity or Overweight: A Randomized Double-Blind, Placebo-Controlled Trial

Eli Lilly and Company

Phase 3 trial evaluating retatrutide once weekly in adults with type 2 diabetes who have obesity or overweight, including a subset with obstructive sleep apnea. Enrolling 1,000 participants across 89 weeks with completion expected May 2026, measuring weight reduction and sleep apnea improvement versus placebo. Eli Lilly advances retatrutide into dual indication territory, competing directly with Novo Nordisk's semaglutide and their own tirzepatide in the expanding cardiometabolic space. The inclusion of sleep apnea patients follows Zepbound's December 2024 OSA approval, positioning retatrutide for multiple obesity comorbidities.

Strategic signal

Eli Lilly positions retatrutide as their next-generation triple agonist to compete with established GLP-1s in type 2 diabetes plus obesity. The dual primary endpoints mirror Zepbound's successful OSA strategy, targeting specialty sleep medicine alongside endocrinology. US CMS and commercial payers will likely require retatrutide to demonstrate superiority over tirzepatide for dual coverage, given Lilly's own internal competition. This trial design suggests Lilly expects retatrutide to deliver differentiated weight loss beyond tirzepatide's 22.5% in SURMOUNT-1.

GLP-1Weight lossType 2 diabetesEli Lilly Novo Nordisk

Original Abstract

The purpose of this study is to is to evaluate the efficacy and safety of retatrutide in participants with type 2 diabetes in participants who have obesity or overweight (J1I-MC-GZBK master protocol) including a subset of participants who have obstructive sleep apnea (OSA) (J1I-MC-GSA2). The study will last about 89 weeks and will include up to 24 visits. | Condition(s): Type 2 Diabetes; Obesity; Overweight; Obstructive Sleep Apnea | Primary endpoint(s): Percent Change from Baseline in Body Weight; Change from Baseline in Apnea-Hypopnea Index (AHI) for GSA2 Subset | Enrollment: 1,000 (estimated) | Phase: Phase 3 | Sponsor: Eli Lilly and Company | Expected completion: 2026-05 | Status: Active Not Recruiting | Last update: 2026-04-13

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