Retatrutide's other trials: sleep apnoea, liver, diabetes

Lilly is testing retatrutide for more than weight. Trials have reported in sleep apnoea, fatty liver disease and type 2 diabetes, and others are running in chronic back pain, liver outcomes, weight maintenance and different ways of stepping up the dose. This page covers each briefly, with what has been shown and what has not.

Obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is when the airway repeatedly closes during sleep. Its severity is measured by the apnoea-hypopnoea index (AHI), the number of breathing interruptions per hour; 30 or more counts as severe. TRIUMPH-1 was a basket trial with a nested group of people who had moderate-to-severe OSA. From a starting average of 58.6 events per hour, retatrutide reduced the AHI by up to 36.1 events per hour, a 60.6% reduction, at 80 weeks.^[1] This was presented at the American Diabetes Association meeting in June 2026 and has not been peer-reviewed. TRIUMPH-2 has a similar nested group in people with diabetes that has not yet been reported. Lilly has said OSA is one of the indications it intends to seek approval for.

Fatty liver disease (MASLD)

MASLD is the build-up of fat in the liver linked to obesity and metabolic problems. It is where retatrutide's glucagon action, explained on the how it works page, is easiest to see.

In a sub-study of the Phase 2 obesity trial, 98 participants with liver fat of 10% or more had it measured by MRI. After 24 weeks, relative liver fat had fallen by 42.9% on 1 mg, 57.0% on 4 mg, 81.4% on 8 mg and 82.4% on 12 mg, against a 0.3% rise on placebo. A normal liver-fat level (under 5%) was reached by 27%, 52%, 79% and 86% of those groups and by none of the placebo group.^[2] This was published in Nature Medicine in 2024 and is peer-reviewed.

Reducing liver fat is another surrogate outcome. Whether it prevents cirrhosis, liver failure or liver-related death is being tested in SYNERGY-Outcomes (NCT07165028), a trial of about 4,500 people with MASLD at raised risk of serious liver disease, which includes both a retatrutide arm and a tirzepatide arm against placebo and measures major adverse liver outcomes over roughly 224 weeks. It is recruiting, with completion estimated around 2030.^[4] Note that these liver findings are about the trial drug lowering liver fat; the liver-injury cluster in Australia involved unlicensed products and is a different matter entirely.

Chronic low back pain

TRIUMPH-7 (NCT07035093) is testing retatrutide in about 586 adults with obesity or overweight and chronic low back pain. It has two primary outcomes, change in pain intensity on a numeric rating scale and percentage change in body weight, measured at up to 72 weeks. Primary completion is estimated for September 2027.^[5] Nothing has been reported.

Type 2 diabetes: the TRANSCEND programme

TRANSCEND-T2D-1 enrolled 537 adults whose type 2 diabetes was not controlled by diet and exercise alone and who were not on any diabetes medicine, in the USA, Mexico and India, for 40 weeks. HbA1c fell by 1.69 to 1.94 percentage points across the three doses against 0.81 on placebo, and weight fell by 11.5% on the lowest dose to 15.3% on the highest. Discontinuation because of side effects was 2.2%, 4.5% and 5.1% versus none on placebo.^[3] This trial was published in The Lancet in June 2026 and is the only Phase 3 retatrutide trial with a peer-reviewed paper. Lilly's presentation of the same data reported that 90% of participants reached an HbA1c below 7.0%.^[1]

The side-effect pattern matched the obesity trials, with nausea, diarrhoea and vomiting leading and dysesthesia at a lower rate than in TRIUMPH-1 or TRIUMPH-4. A caution on reading this trial: participants were taking no other diabetes medicine, so the numbers do not describe people on metformin or insulin.

TRANSCEND-T2D-2 (NCT06260722) compares retatrutide with semaglutide in about 1,250 adults with type 2 diabetes on metformin, with or without an SGLT2 inhibitor. Its primary outcome is change in HbA1c at 80 weeks. Unlike most retatrutide trials it is open-label, meaning participants and staff know which drug is being given, which makes any difference in reported side effects harder to interpret. Primary completion is estimated for August 2026, so a topline result may arrive soon.^[6] As with TRIUMPH-5, no comparison with semaglutide can be made until it reports.

TRANSCEND-T2D-3 (NCT06297603) tests retatrutide against placebo in about 320 adults with type 2 diabetes and moderate or severe kidney impairment who are on basal insulin. Its primary outcome is HbA1c at 52 weeks, with completion estimated for October 2026.^[7] This is the first retatrutide trial in people with significantly reduced kidney function, a group every earlier trial excluded, so it matters for safety as much as for blood sugar. See liver and kidney. For the main diabetes-and-obesity trial, see TRIUMPH-2.

Weight maintenance

Nobody yet knows what happens to weight when retatrutide is stopped. With earlier drugs in the class, most of the lost weight returned within a year. TRIUMPH-6 (NCT06859268) is designed to answer the question for retatrutide: about 643 adults with obesity take the drug for 80 weeks, then are assigned to continue on the same dose, switch to a different dose, or switch to placebo, for a further 36 weeks, with weight at 116 weeks as the primary outcome. Completion is estimated for April 2028.^[8] The plateaus and maintenance page covers what is known from other drugs.

Dose escalation and a smaller obesity trial

TRIUMPH-9 (NCT07357415) is a trial in about 600 adults comparing different escalation approaches, with weight at 104 weeks as the primary outcome and completion estimated for October 2028.^[9] That is all this site will say about it: how a dose is stepped up is a question for the trial and, eventually, for a licensed product's instructions, not for a website. TRIUMPH-8 (NCT07232719) is a further trial in about 250 adults with obesity without diabetes, due to complete around July 2027.^[10]