Trial Results Show Retatrutide Lowers Weight and Blood Sugar in Adults With Type 2 Diabetes
Adults with obesity and type 2 diabetes achieved an average body weight loss of up to 18.8% at 80 weeks while taking the investigational triple hormone receptor agonist retatrutide, according to phase III trial results published in The Lancet and presented at the European Association for the Study of Diabetes annual meeting. The international, double-blind TRIUMPH-2 trial evaluated 1,152 participants across 92 medical and research centers in eight countries, testing once-weekly subcutaneous injections of 4 mg, 9 mg, or 12 mg doses against a placebo.
Retatrutide Doses Drive Significant Body Weight Loss
Under the treatment-regimen estimand, participants taking 4 mg of retatrutide lost an average of 11.9% of their body weight, those on the 9 mg dose lost 16.8%, and those on the 12 mg dose lost 18.8%, compared with a 5.1% weight loss in the placebo group. Under the efficacy estimand, which assumes all participants took the medication without intercurrent events, weight loss reached 20.8% at the 12 mg dose. Juan P. Frias, MD, of the Los Angeles Institute for Metabolic Research, noted that more than 50% of patients in that analysis achieved greater than 15% weight loss.
In addition to weight reduction, the trial tracked significant drops in hemoglobin A1c levels among patients taking background diabetes therapy. Average drops in HbA1c starting from a 7.71% baseline hit -1.38% with the 4-mg dose, -1.50% with the 9-mg dose, and -1.45% with the 12-mg dose, compared to a -0.45% drop for the placebo group. Up to 40% of patients treated with retatrutide reached normoglycemia, defined as an HbA1c under 5.7%.
Comparison With Other Incretin Therapies and Mechanism of Action
Retatrutide differs from currently approved incretin-based drugs by targeting three distinct hormone receptors instead of one or two. Semaglutide targets the GLP-1 receptor, while tirzepatide acts on both GIP and GLP-1 receptors. Retatrutide adds glucagon (GCG) receptor activity to GIP and GLP-1 agonism, creating a triple mechanism that researchers report increases energy expenditure and fat breakdown alongside appetite suppression.
Eli Lilly and Company is developing the therapy, which is also undergoing phase III evaluation for knee osteoarthritis pain, obstructive sleep apnea, and metabolic dysfunction-associated steatotic liver disease.
Retatrutide Improves Cardiometabolic Markers with Mild Side Effects
Participants receiving retatrutide experienced notable improvements across secondary cardiometabolic endpoints, including waist circumference reductions of up to 15.4 cm. Reductions also reached 35.6% for triglycerides, 16.5% for non-HDL cholesterol, and 56.1% for high-sensitivity C-reactive protein.
Gastrointestinal events such as nausea, diarrhea, and constipation were the most frequent side effects, though discontinuations specifically due to these GI symptoms remained low at 0% to 2% for retatrutide versus 1% for placebo.
FDA Has Not Approved Retatrutide for Use
Retatrutide remains an investigational drug that has not received approval from the U.S. Food and Drug Administration. The medication is restricted to clinical trial participants and cannot be legally prescribed, purchased, or compounded outside of those studies. Any formulation of retatrutide acquired outside the bounds of a clinical trial lacks authenticity and poses potential risks to your physical well-being.