Retatrutide Results in the Clinical Trials

The quick read

Retatrutide results from Phase 2 trials showed the largest weight-loss numbers recorded for any drug in that evidence class at the time of publication. Retatrutide is a triple agonist — it activates three hormone receptors instead of one or two — and the cardiometabolic results reflect that broader target coverage.

This page pulls together the key outcomes from Phase 1b through Phase 2 across weight, blood sugar, liver fat, blood pressure, and lipids. Every figure is cited to a published study. Retatrutide is investigational and not approved, so these are trial outcomes, not prescribing data. If you want the mechanism context, the Retatrutide research page covers it in detail.

Weight outcomes: Phase 2 obesity trial

The 48-week Phase 2 obesity trial (Jastreboff et al., N Engl J Med, 2023) reported mean body-weight changes by dose arm at 48 weeks ^[1]:

• 12 mg: -24.2% (vs -2.1% placebo)
• 8 mg: -22.8%
• 4 mg: -17.3%
• 1 mg: -8.7%

Participants: 338 adults with obesity (BMI ≥30) or overweight (BMI 27-<30) with a weight-related comorbidity.

A 2026 review in Cardiology in Review confirmed: 63% of participants reached ≥20% total body weight loss at the 12 mg dose; waist circumference fell by nearly 20 cm ^[12]. Phase 1 proof-of-concept studies had already established dose-escalation feasibility, with Phase 2 then demonstrating up to ~24% body weight reduction ^[10].

A 2025 Biomolecules review characterized the -24.2% figure as a step-change in incretin pharmacotherapy, approaching bariatric surgery weight loss in a pharmacological vehicle ^[6]. A 2024 Cell review on multi-receptor drugs positioned the 20-30% weight-loss band as what triple agonism over dual or single agonism makes accessible ^[11].

Glycemic outcomes: Phase 2 type 2 diabetes trial

The 36-week Lancet Phase 2 diabetes trial (Rosenstock et al., 2023) reported ^[2]:

• HbA1c reduction at 12 mg: -2.02% vs -0.01% placebo at 24 weeks.
• Body weight reduction: -16.94% vs -3.00% placebo at 36 weeks.
• No severe hypoglycemia, no deaths.
• GI adverse events (mild to moderate) in 35%.

HbA1c is glycated hemoglobin — a blood marker that reflects average blood glucose over approximately three months. A 2.02% absolute reduction in HbA1c at 24 weeks represents a clinically meaningful improvement in glucose control. This is the retatrutide GIP/GLP-1R arm's primary metabolic contribution: enhanced glucose-dependent insulin secretion and improved peripheral insulin sensitivity.

Liver outcomes: Phase 2 MASLD substudy

The dedicated MASLD (metabolic dysfunction-associated steatotic liver disease — fatty liver disease linked to metabolic risk) substudy (Sanyal et al., Nature Medicine, 2024) reported relative liver-fat changes by MRI-PDFF at 24 weeks ^[5]:

• 12 mg: -82.4% (vs +0.3% placebo)
• 8 mg: -81.4%
• 4 mg: -57.0%
• 1 mg: -42.9%

86% of participants at 12 mg reached normal liver fat (<5%) at 24 weeks. Reductions were sustained to 48 weeks (-86.0% at 12 mg).

The glucagon receptor-driven hepatic lipid metabolism is likely the primary driver: GCGR activation increases hepatic fat oxidation and export, addressing the root metabolic defect in MASLD. This is among the most striking single-organ findings in the retatrutide program.

Cardiometabolic outcomes: blood pressure, lipids, kidney markers

A 2026 review in Cardiology in Review synthesized the CKM (cardiovascular-kidney-metabolic) syndrome evidence ^[12]:

• Systolic blood pressure: -8.79 mmHg in the Phase 2 obesity trial.
• 24.2% total body weight loss at 48 weeks; 63% reaching ≥20% TBW loss.
• HbA1c: -2.02% in the T2D Phase 2 trial.
• Urine albumin-to-creatinine ratio: significantly attenuated — a kidney-health marker.

A 2026 incretin blood-pressure meta-analysis (Basile et al., Eur J Prev Cardiol) found triple agonists reduced systolic blood pressure by 6.6 mmHg and diastolic by 2.1 mmHg; all-cause mortality reduced 18% (RR 0.82) across the class ^[14].

Lipid effects: a 2025 study found ANGPTL3/8 reductions (proteins that limit fat-clearing enzyme activity) at 8 and 12 mg in type 2 diabetes and across all doses in obesity; reductions paralleled decreases in triglycerides and LDL-C ^[15]. Changes in fatty acid oxidation cluster mediated 23.2% of the weight-reduction response in non-diabetic participants ^[13].

The class-level cardiovascular signal from a 2025 meta-analysis of 29 RCTs (n=37,348) found GLP-1-based therapies reduced total cardiovascular events (RR 0.81), MACE (RR 0.80), myocardial infarction (RR 0.72), and all-cause mortality (RR 0.81) ^[7]. Retatrutide was highlighted as most effective in improving lipid profiles within the analysis ^[7]. Dedicated cardiovascular outcome trial results are pending.

Phase 3 and open questions

The retatrutide results from Phase 2 are large and consistent across metabolic endpoints. What they do not yet show is whether those metabolic improvements translate to reduced cardiovascular events, reduced kidney disease progression, or sustained weight loss after discontinuation. Those are the questions Phase 3 is designed to answer.

Pipeline reviews in 2025 positioned retatrutide as approaching bariatric surgery weight loss within a pharmacological formulation, with early Phase 3 data reinforcing the Phase 2 weight signal ^[8]. Final outcome trial results will determine the compound's standing in the therapeutic landscape. This site tracks those results as they publish. See retatrutide vs tirzepatide for how these results compare to the current standard of care.