InterventionsHuman trial1,152 participants80 weeksRandomised trial

Retatrutide reduces bodyweight in obesity and type 2 diabetes

Bodyweight fell by up to 18.8% with weekly retatrutide compared with 5.1% on placebo at week 80 in adults with obesity and type 2 diabetes.

Figure 1 from Lancet — Figure 1Bellido et al.

Lancet4 Oct 2026, 08:19 BST

In a phase 3 trial of 1152 adults with obesity and type 2 diabetes, participants received weekly injections of placebo or the GIP, GLP-1, and glucagon receptor agonist retatrutide at doses of 4 mg, 9 mg, or 12 mg for 80 weeks. Mean bodyweight fell 11.9% with 4 mg, 16.8% with 9 mg, and 18.8% with 12 mg retatrutide, compared with 5.1% on placebo. Estimated treatment differences versus placebo ranged from -6.9% to -13.8% (all p<0.0001). Treatment was also associated with improvements in glycaemic control. Gastrointestinal adverse events, mainly diarrhoea and nausea, were most frequent with retatrutide. Hypotension and dysesthesia were also more common on the drug.

Why it matters

Retatrutide is currently under study for comorbidities that include knee osteoarthritis and obstructive sleep apnoea. Marked weight loss and improved glycaemic control in adults with obesity and type 2 diabetes could be relevant to managing these comorbid conditions.

Caveats

Adverse events led to higher permanent treatment discontinuation at higher doses, reaching 12% with 9 mg and 8% with 12 mg compared with 5% on placebo. Overall, 16% of participants did not complete the 80-week drug regimen.