Retatrutide, an experimental Eli Lilly injection that acts on three hormone receptors at once, produced average weight loss of up to 18.8% over 80 weeks in adults with type 2 diabetes and obesity or overweight, according to the Phase 3 TRIUMPH-2 trial published in The Lancet and presented at the European Association for the Study of Diabetes annual meeting in Milan, held from 28 September to 2 October 2026. The double-blind trial randomised 1,152 participants to retatrutide 4 mg, 9 mg or 12 mg or to placebo, with all groups given dietary counselling and physical activity guidance. Weight fell by 11.9% on the 4 mg dose, 16.8% on 9 mg and 18.8% on 12 mg, against 5.1% on placebo. NBC News reported that HbA1c dropped by up to 1.6 percentage points compared with 0.2 on placebo, and that up to 40% of participants reached an HbA1c below 5.7%. The trial was funded by Eli Lilly, which developed the drug.
Side effects and the regulatory position
Gastrointestinal effects were common. Diarrhoea was reported by 27% to 34% of participants on retatrutide against 13% on placebo, and nausea by 14% to 28% against 8%. Dysesthesia, an altered or unpleasant skin sensation, affected 4% to 7% against 1% on placebo. Discontinuation because of adverse events reached 12% on the 9 mg dose. Retatrutide is not licensed by any medicines regulator, including the MHRA, and NBC News reported that Lilly plans to file for US approval early next year. Supplying an unlicensed medicine is an offence under the Human Medicines Regulations 2012, which apply UK-wide.
What this means in practice
Trial results do not change the legal status of the vials already being sold as "reta" through UK gyms and social media, which the MHRA has been seizing in enforcement operations. An unapproved drug with published Phase 3 data is still an unapproved drug, and the trial figures above came from monitored participants on manufactured doses, not from an unverified product bought online. Food supplements, including everything in Perqen's catalogue, sit under food law rather than medicines law. They are a different category of product and none is an alternative to a prescribed treatment. Suspected side effects from any medicine can be reported through the MHRA Yellow Card scheme.
How Perqen members save
Perqen is a membership retailer selling food supplements from established brands sourced through an authorised EU distributor. It does not sell prescription or unlicensed medicines.
This article reports published news and research and is for information only. Food supplements are not a substitute for a varied diet or medical care, and no product mentioned is intended to diagnose, treat, cure or prevent any disease. Speak to your GP or pharmacist before changing what you take, especially if you are pregnant, breastfeeding, or taking prescribed medicines.
Sources
- Retatrutide in adults with obesity and type 2 diabetes (TRIUMPH-2): a double-blind, parallel-group, randomised, placebo-controlled, phase 3 trial, The Lancet
- New triple agonist drug produces substantial weight loss in diabetic patients
- People with Type 2 diabetes lost up to 60 pounds on Lilly's latest weight loss drug