Research information only, not medical advice. Retatrutide (LY-3437943) is an investigational once-weekly injectable triple agonist of the GLP-1, GIP, and glucagon receptors, developed by Eli Lilly. It is not approved by the US FDA; a regulatory submission is anticipated around Q4 2026 to Q1 2027.
Retatrutide at a glance
The evidence base consists of randomized controlled trials in adults with obesity. In a 48-week phase 2 trial, retatrutide 12 mg produced a mean body-weight reduction of about 24% at 48 weeks (Jastreboff et al., NEJM 2023). In the phase 3 TRIUMPH-1 trial (80 weeks, adults with obesity without type 2 diabetes), retatrutide 12 mg produced a mean weight reduction of about 28% (up to 30.3%) per an Eli Lilly news release. A separate randomized phase 2a trial evaluated retatrutide for metabolic dysfunction-associated steatotic liver disease (MASLD). The most common adverse effects are gastrointestinal (nausea, vomiting, diarrhea), consistent with the GLP-1 receptor agonist class.
See how we grade evidence for the methodology behind this page.
Evidence profile
85 studies- Human RCT 6 · 7%
- Human trial 4 · 5%
- Review 42 · 49%
- Animal 19 · 22%
- In-vitro 4 · 5%
- Unknown 10 · 12%
The longer the green, the stronger the human evidence. For most research peptides the bar is dominated by animal and in-vitro work, which is a signal to read every claim carefully.
Regulatory status
Clinical trials
-
A Safety Study of LY3437943 Given as a Single Injection in Healthy Participants
-
A Study of LY3437943 in Participants With Type 2 Diabetes Mellitus (T2DM)
-
A Study of LY3437943 in Japanese Participants With Type 2 Diabetes Mellitus (T2DM)
-
A Study of LY3437943 in Participants With Type 2 Diabetes
-
A Study of LY3437943 in Participants Who Have Obesity or Are Overweight
-
A Drug-Drug Interaction (DDI) Study of LY3437943 in Obese Participants
-
A Study of LY3437943 in Chinese Participants With Obesity Or Overweight
-
A Study of LY3437943 in Healthy Participants and Participants With Impaired Renal Function
-
A Study of Retatrutide (LY3437943) in Participants With Obesity and Cardiovascular Disease
-
A Study of LY3437943 in Participants With Impaired and Normal Liver Function
-
A Study of Retatrutide (LY3437943) in Participants Who Have Obesity or Overweight
-
A Study of Retatrutide (LY3437943) in Participants With Type 2 Diabetes Mellitus Who Have Obesity or Overweight
-
A Study of Retatrutide (LY3437943) Once Weekly in Participants Who Have Obesity or Overweight and Osteoarthritis of the Knee
-
A Study of Retatrutide (LY3437943) on Renal Function in Participants With Overweight or Obesity and Chronic Kidney Disease With or Without Type 2 Diabetes
-
A Study of LY3437943 in Healthy Participants With a High Body Mass Index
-
A Research Study Looking at Similarity Between LY3437943 Versions for Different Injection Devices
-
A Study of LY3437943 in Postmenopausal Female Participants Who Are Overweight or Obese
-
Effect of Retatrutide Compared With Semaglutide in Adult Participants With Type 2 Diabetes and Inadequate Glycemic Control With Metformin With or Without SGLT2 Inhibitor (TRANSCEND-T2D-2)
-
Effect of Retatrutide Compared With Placebo in Participants With Type 2 Diabetes and Moderate or Severe Renal Impairment, With Inadequate Glycemic Control on Basal Insulin, With or Without Metformin and/or SGLT2 Inhibitor (TRANSCEND-T2D-3)
-
A Study to Measure Calorie Consumption and Usage in Participants With Obesity Using LY3437943
-
Effect of Retatrutide Compared With Placebo in Adult Participants With Type 2 Diabetes and Inadequate Glycemic Control With Diet and Exercise Alone (TRANSCEND-T2D-1)
-
The Effect of Retatrutide Once Weekly on Cardiovascular Outcomes and Kidney Outcomes in Adults Living With Obesity (TRIUMPH-Outcomes)
-
A Study of Retatrutide (LY3437943) Compared to Tirzepatide (LY3298176) in Adults Who Have Obesity
-
To Investigate the Effect of Retatrutide (LY3437943) on Metoprolol Pharmacokinetics in Healthy Participants
-
A Study of Retatrutide (LY3437943) in the Maintenance of Weight Reduction in Individuals With Obesity
-
A Study to Investigate the Response of Participants With Type 2 Diabetes Mellitus on Once-Weekly Retatrutide to Hypoglycemia
-
A Study to Evaluate the Effect of Retatrutide on Insulin Secretion and Insulin Sensitivity in Adult Participants With Type 2 Diabetes Mellitus
-
A Study of Retatrutide (LY3437943) in Participants Who Have Obesity or Overweight and Chronic Low Back Pain
-
A Master Protocol of Multiple Agents in Adults With Metabolic Dysfunction-Associated Steatotic Liver Disease (SYNERGY-Outcomes)
-
A Study of Retatrutide (LY3437943) in Participants With Obesity or Overweight
-
A Study of Retatrutide (LY3437943) in Participants Without Type 2 Diabetes Who Have Obesity or Overweight
-
Effect of LY3437943 Versus Placebo in Participants Who Have Obesity or Are Overweight
- NCT07629401 AVAILABLE
Provide Pre-approval Expanded Access of LY3437943
Indexed research
Sorted by evidence level, strongest first.
- Human RCT 2026Efficacy 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
- Human RCT 2026Rationale, design and baseline characteristics of the TRANSCEND-CKD trial of retatrutide in patients with chronic kidney disease
This article describes the rationale, design, and baseline characteristics of the TRANSCEND-CKD trial, a Phase 2b double-blind, placebo-controlled study evaluating the effects of retatrutide in patients with chronic kidney disease.
- Human RCT 2026Retatrutide And Lipid And Metabolite Profiles In Participants With Obesity With Or Without Type 2 Diabetes
Retatrutide treatment in phase 2 trials of participants with obesity with or without type 2 diabetes was associated with changes in metabolites related to fatty acid oxidation and insulin resistance, suggesting improved metabolic health and reduced cardiovascular risk.
- Human RCT 2025Appetite, eating attitudes, and eating behaviours during treatment with retatrutide in adults with type 2 diabetes: Results of a phase 2 study
- Human RCT 2026TRANSCEND-T2D-1 and the First-Line Question: What Retatrutide's Phase 3 Results Mean for Diabetes Care, Access & Equity
The TRANSCEND-T2D-1 trial demonstrated that retatrutide, a triple agonist, significantly reduced HbA1c and body weight in type 2 diabetes patients but with increased adverse events and high costs.
- Human RCT 2026TRANSCEND-T2D-1 and the First-Line Question: What Retatrutide's Phase 3 Results Mean for Diabetes Care, Access & Equity
The TRANSCEND-T2D-1 trial demonstrates that retatrutide, a triple agonist, significantly reduces HbA1c and body weight in adults with type 2 diabetes but raises concerns about adverse events, cost, and equitable access.
- Human trial 2026Retatrutide: Triple acting jab for type 2 diabetes lowers blood sugar and boosts weight loss, trial reports
This study reports on the effects of Retatrutide, a triple-acting agent, in lowering blood sugar and promoting weight loss in patients with type 2 diabetes based on trial results.
- Human trial 2025Perceived benefits of treatment for obesity with retatrutide: A qualitative study of patients in a phase 2 clinical trial
The study found that patients with obesity or overweight treated with retatrutide in a phase 2 trial reported early changes in eating behavior, improved well-being, and weight loss goal achievement, with some reporting adverse social effects or frustration.
- Human trial 2026Data from: Retatrutide And Lipid And Metabolite Profiles In Participants With Obesity With Or Without Type 2 Diabetes
This study investigates the impact of retatrutide on lipid and metabolite profiles in individuals with obesity, with or without type 2 diabetes.
- Human trial 2026Data from: Retatrutide And Lipid And Metabolite Profiles In Participants With Obesity With Or Without Type 2 Diabetes
This study reports the effects of retatrutide on lipid and metabolite profiles in obese participants with or without type 2 diabetes.
+ 75 more studies indexed for Retatrutide.
Frequently asked questions
- Is Retatrutide approved for human use?
- Retatrutide (LY-3437943) is an investigational once-weekly injectable triple agonist of the GLP-1, GIP, and glucagon receptors, developed by Eli Lilly. It is not approved by the US FDA; a regulatory submission is anticipated around Q4 2026 to Q1 2027.
- What does the research on Retatrutide show?
- The evidence base consists of randomized controlled trials in adults with obesity. In a 48-week phase 2 trial, retatrutide 12 mg produced a mean body-weight reduction of about 24% at 48 weeks (Jastreboff et al., NEJM 2023). In the phase 3 TRIUMPH-1 trial (80 weeks, adults with obesity without type 2 diabetes), retatrutide 12 mg produced a mean weight reduction of about 28% (up to 30.3%) per an Eli Lilly news release. A separate randomized phase 2a trial evaluated retatrutide for metabolic dysfunction-associated steatotic liver disease (MASLD). The most common adverse effects are gastrointestinal (nausea, vomiting, diarrhea), consistent with the GLP-1 receptor agonist class.