Eli Lilly’s Triple-Agonist Retatrutide Delivers Record Weight-Loss and Multi-Organ Benefits in Phase 3 Trials

Eli Lilly, already leading with Zepbound (tirzepatide) and Mounjaro, presented data on retatrutide—a triple GLP-1/GIP/glucagon receptor agonist—at the American Diabetes Association 2026 Scientific Sessions in New Orleans. The drug is intended to treat obesity and its metabolic complications together. The findings were released as a press briefing and a poster abstract at the meeting.

The Independent

In the 40-week TRANSCEND-T2D-1 trial (537 participants), retatrutide lowered A1c by 1.69%–1.94% versus 0.81% with placebo and reduced weight by 11.5%–15.3% (?36 lb) versus 2.6% placebo. The 80-week TRIUMPH-1 obesity trial (2,339 participants) showed 28.3% weight loss (?70 lb) at 12 mg, extending to 30.3% (?85 lb) at 104 weeks; 65.3% reached BMI < 30 kg/m². Secondary outcomes included up to 73% reduction in knee-pain WOMAC scores, 60% drop in apnea-hypopnea index, and 12-mm Hg systolic-BP reductions. Nausea occurred in up to 42% (12 mg) and urinary-tract infections rose to 8% versus 3% placebo.

Medscape

Ania Jastreboff, MD, PhD, said obesity drives >200 downstream diseases and that retatrutide “demonstrates what may be possible when we treat obesity and impact overall health.” Harpreet Singh Bajaj, MD, called the weight-loss magnitude “not been seen with any medications in a phase 3 study before.” Lilly’s Kenneth Custer, president of Cardiometabolic Health, described the data as showing “potential across the cardiometabolic spectrum.” RBC and UBS analysts said the results could reinforce Lilly’s market lead but stressed the need for longer-term safety data.

BioSpace

Alice YY Cheng, MD, warned that “bigger is not always needed,” questioning whether extreme weight loss translates to health gain. Naveed Sattar, MD, cautioned that rapid weight loss may cause harm and linked the urinary-tract infection signal to possible diuresis. Gastro-intestinal tolerability was higher than with Zepbound, raising concerns about broader use.

Medscape

TRIUMPH-1 results have not yet been published in a peer-reviewed journal, limiting independent verification. The Lancet report noted 2% of low-dose diabetes patients experienced major adverse cardiovascular events, with causality undetermined.

Medscape

Lilly plans to file regulatory submissions after the 104-week data and will present additional safety analyses at upcoming ADA meetings and in forthcoming peer-reviewed publications.

BioPharmaDive

• “That is quite staggering,” — Harpreet Singh Bajaj, MD

Medscape

• “Obesity drives more than 200 downstream diseases, yet we have historically treated those conditions one at a time and in silos,” — Ania Jastreboff, MD, PhD

Medscape

• “I think [this] study is exciting. The penny is dropping that we need to tackle obesity much more aggressively in T2D. This is now another tool to allow us to do that beyond semaglutide and tirzepatide.” — Naveed Sattar, MD

Medscape

• “a highly impressive number and not one we have seen before from a pharmacotherapy.” — Alice YY Cheng, MD

Medscape