ADA 2026: First-line retatrutide drives normal A1C in nearly half of T2D patients

Clinical takeaway: The treatment-naive trial design raises a question already circulating around GLP-1 class agents: should the most effective metabolic therapies be deployed first, not last? Retatrutide is not yet approved, but results like these will sharpen that debate.

When retatrutide weight-loss data landed in May, the results approached bariatric surgery territory. New phase 3 results presented at American Diabetes Association (ADA) 86th Scientific Sessions and published in The Lancet now add a different dimension: substantial glycemic control in drug-naive adults with type 2 diabetes. That's alongside additional data showing meaningful reductions in sleep apnea severity and knee pain.

Retatrutide delivered substantial glycemic and weight reductions across all three doses in TRANSCEND-T2D-1, a 40-week placebo-controlled trial in 537 drug-naive adults with type 2 diabetes inadequately controlled by diet and exercise alone. Mean baseline A1C was 7.9%.

The drug candidate reduced A1C by 1.69%, 1.86%, and 1.94% across the 4 mg, 9 mg, and 12 mg doses, versus 0.81% with placebo. Up to 90% reached the ADA general target of below 7.0%, and 46% achieved normoglycemia, defined as A1C below 5.7%. Weight loss reached 16.8% (36.6 lbs) with the 12 mg dose at 40 weeks, with no plateau in sight.

TRIUMPH-1 basket trial data, also presented at ADA, extend that picture further. In participants with knee osteoarthritis, retatrutide 12 mg reduced pain scores by 4.3 points from a baseline of 6.0, a 73.1% reduction. In those with moderate-to-severe obstructive sleep apnea, the apnea-hypopnea index dropped by 36.1 events per hour from a baseline of 58.6, a 60.6% reduction. Both are clinically meaningful thresholds. Retatrutide also improved triglycerides, non-HDL cholesterol, systolic blood pressure, and waist circumference across both trials.

Adverse events were consistent with the GLP-1 class. Gastrointestinal effects including nausea, diarrhea, vomiting were the most common and generally mild to moderate, resolving over time in most patients. Discontinuation due to adverse events ranged from 2% to 11% with retatrutide depending on dose and trial, versus 0% to 4.9% with placebo. No severe hypoglycemia was reported in TRANSCEND-T2D-1.

Lilly hasn't announced a regulatory submission timeline. Cardiovascular and renal outcomes trials are ongoing, and additional TRIUMPH program data are expected later this year.

"Obesity drives more than 200 downstream diseases, yet we have historically treated those conditions one at a time and in silos," said Ania Jastreboff, M.D., Ph.D., Professor of Medicine & Pediatrics (Endocrinology) at the Yale School of Medicine, Director of the Yale Obesity Research Center (Y-Weight), and lead investigator. "In TRIUMPH-1 and TRANSCEND-T2D-1, treatment with retatrutide resulted in substantial weight reduction together with clinically meaningful improvements in glycemia, knee osteoarthritis pain, and obstructive sleep apnea, with many individuals reaching what are classified as healthy-range weight and normal blood sugar levels."

She concluded, "These findings demonstrate what may be possible when we treat obesity and impact overall health, and what this could mean for people living with obesity and its related complications."

Source: Bajaj HS, et al. The Lancet. June 6, 2026. Efficacy and safety of retatrutide, a GIP, GLP-1, and glucagon receptor agonist, in people with type 2 diabetes and inadequate glycaemic control with diet and exercise (TRANSCEND-T2D-1): a double-blind, randomised, phase 3 trial