Retatrutide research initially attracted attention because of the amount of weight participants lost.
But the Phase 3 research program is increasingly asking a different question:
What happens to the health conditions associated with obesity when body weight falls by 20%, 25%, or even more?
By mid-2026, retatrutide had produced reported improvements in several areas beyond the number on the scale, including:
- systolic blood pressure
- triglycerides
- non-HDL cholesterol
- waist circumference
- knee osteoarthritis pain
- physical function
- obstructive sleep apnea severity.
These findings are scientifically important. But they also require careful interpretation.
Some results come from peer-reviewed clinical trials. Others currently come from Phase 3 conference presentations and company-reported topline data. And even when an outcome improves substantially, the trials may not reveal whether retatrutide has a direct effect on that condition or whether the improvement is largely mediated by weight loss.
TL;DR
Current retatrutide research has reported:
- triglyceride reductions of up to about 41% in TRIUMPH-1
- non-HDL cholesterol reductions of up to about 24%
- systolic blood-pressure reductions of up to about 12 mmHg in TRIUMPH-1
- reductions of about 14 mmHg in the 12 mg group of TRIUMPH-4
- waist-circumference reductions of up to about 24 cm
- more than 60% reductions in sleep-apnea events in one TRIUMPH-1 subgroup
- roughly 70% or greater reductions in knee osteoarthritis pain scores at higher doses in Phase 3 analyses.
These are promising intermediate and disease-related outcomes.
They do not yet prove that retatrutide prevents heart attacks, strokes, kidney failure, joint replacement, or cardiovascular death.
A dedicated cardiovascular and kidney outcomes trial involving about 10,000 participants is underway, with completion currently estimated for 2029.
Cardiometabolic Improvements Appeared Early in Development
The first major evidence came from the Phase 2 obesity trial published in 2023.
Researchers did not only track body weight.
Exploratory outcomes included:
- systolic blood pressure
- diastolic blood pressure
- A1C
- fasting glucose
- fasting insulin
- lipid levels
- waist circumference.
Retatrutide improved most of those cardiometabolic measures relative to placebo. HDL cholesterol was the main lipid exception.
The results suggested that substantial weight reduction was occurring alongside broader metabolic changes.
Blood Pressure Fell in the Phase 2 Trial
One particularly interesting finding involved antihypertensive medications.
Among participants receiving the combined 8 mg retatrutide regimens, 41% were able to discontinue at least one antihypertensive medication during the 48-week trial.
The corresponding figure in the 12 mg group was 30%.
That does not prove retatrutide directly treats hypertension.
Body-weight reduction itself can reduce blood pressure.
Changes in dietary intake, insulin sensitivity, sodium handling, medication management, and other factors can also contribute.
But it showed early that the physiological effects extended beyond body weight.
Phase 3 Confirmed Large Blood-Pressure Changes
The larger Phase 3 TRIUMPH-1 trial strengthened that signal.
At 80 weeks, Lilly reported that retatrutide produced reductions of up to:
- 12.3 mmHg in systolic blood pressure
- 24.1 cm, or about 9.5 inches, in waist circumference.
TRIUMPH-4, which studied adults with obesity or overweight and knee osteoarthritis, reported an even larger systolic blood-pressure change at the highest dose.
The 12 mg group had a reported mean systolic blood-pressure reduction of 14.0 mmHg under the efficacy estimand.
Those are substantial changes in a cardiovascular risk factor.
But blood pressure is still a surrogate or intermediate risk marker.
Lower blood pressure strongly matters clinically, but a clinical trial must directly count cardiovascular events before we can say that a drug reduces heart attacks, strokes, or cardiovascular death.
Retatrutide Has Also Changed Lipid Profiles
The lipid findings have been notable as well.
In TRIUMPH-1, retatrutide produced reductions of up to:
- 41.0% in triglycerides
- 24.2% in non-HDL cholesterol.
The Phase 3 TRANSCEND-T2D-1 diabetes study reported reductions of up to:
- 39.6% in triglycerides
- 19.8% in non-HDL cholesterol.
Non-HDL cholesterol represents cholesterol contained within atherogenic lipoproteins other than HDL.
Triglycerides are another metabolic risk marker that often improves when insulin sensitivity, liver fat, visceral fat, and body weight improve.
These changes therefore fit the broader metabolic pattern seen throughout the retatrutide program.
Why Might Triglycerides Improve?
There is probably no single mechanism.
Substantial weight loss can improve triglyceride metabolism.
Reduced visceral adiposity and improved insulin sensitivity can also decrease the flow of fatty acids into the liver.
Retatrutide additionally activates the glucagon receptor, which has been linked experimentally to hepatic lipid oxidation and lipid metabolism.
But the clinical trials do not currently tell us how much of the triglyceride reduction comes from:
- body-weight reduction
- reduced calorie intake
- improved insulin sensitivity
- decreased liver fat
- direct receptor-mediated effects.
Those mechanisms probably overlap.
Waist Circumference Is Another Useful Signal
Scale weight does not tell researchers where fat is being lost.
Waist circumference provides a rough measure related to abdominal adiposity.
In the original Phase 2 obesity trial, mean waist-circumference reductions ranged from approximately 6.5 cm to 19.6 cm across retatrutide groups, compared with 2.6 cm with placebo.
Phase 3 TRIUMPH-1 later reported reductions as large as 24.1 cm at 80 weeks.
That finding is consistent with the body-composition and liver-fat studies showing large reductions in adipose tissue.
Retatrutide and Obstructive Sleep Apnea
Obstructive sleep apnea, or OSA, is one of the most interesting newer areas in the retatrutide program.
OSA occurs when the upper airway repeatedly narrows or closes during sleep.
Severity is commonly measured using the apnea-hypopnea index, or AHI.
AHI measures the number of apnea and hypopnea events occurring per hour of sleep.
Higher numbers indicate more severe sleep-disordered breathing.
What Did TRIUMPH-1 Find for Sleep Apnea?
TRIUMPH-1 included an obstructive sleep apnea subgroup, sometimes described as an OSA basket.
Participants had a baseline AHI of approximately 58.6 events per hour, indicating substantial sleep apnea severity.
At 80 weeks, reported AHI changes under the efficacy estimand were:
| Group | Absolute AHI Change | Approximate Reduction |
|---|---|---|
| Placebo | -11.1 events/hour | -16% |
| Retatrutide 4 mg | -25.7 | -44% |
| Retatrutide 9 mg | -36.1 | -61% |
| Retatrutide 12 mg | -33.8 | -58% |
The 9 mg group therefore showed a reduction of slightly more than 60% in apnea-hypopnea events.
Those are large changes.
Does That Mean Retatrutide Directly Treats the Airway?
Not necessarily.
Obesity is an important risk factor for obstructive sleep apnea.
Fat distribution around the neck and upper airway, abdominal fat, lung volume, airway mechanics, and other metabolic factors can influence OSA severity.
Substantial weight reduction can therefore reduce the number of obstructive events during sleep.
TRIUMPH-1 demonstrates that retatrutide treatment was associated with large improvements in OSA severity.
It does not establish that retatrutide has a unique direct pharmacological effect on airway anatomy or respiratory control independent of weight loss.
That distinction should remain clear until mechanistic analyses are available.
Retatrutide and Knee Osteoarthritis
Knee osteoarthritis is another condition strongly influenced by body weight.
Excess body mass increases mechanical loading across the knee joint.
Obesity may also contribute through systemic inflammation and metabolic pathways.
That makes knee osteoarthritis a logical condition to study alongside large-scale weight reduction.
Retatrutide has now been evaluated in two relevant Phase 3 settings.
TRIUMPH-4 Was Designed Specifically Around Knee Osteoarthritis
TRIUMPH-4 studied adults with obesity or overweight and knee osteoarthritis who did not have diabetes.
The trial used the WOMAC pain scale.
WOMAC stands for the Western Ontario and McMaster Universities Osteoarthritis Index.
It is a validated patient-reported assessment that evaluates areas including:
- pain
- stiffness
- physical function.
At baseline, the average WOMAC pain score was approximately 6.0 on a normalized 0-to-10 scale.
Pain Fell Substantially
At 68 weeks, the reported changes were:
| Group | WOMAC Pain Change |
|---|---|
| Retatrutide 9 mg | -4.5 points |
| Retatrutide 12 mg | -4.4 points |
| Placebo | -2.4 points |
That represented approximately:
- 75.8% reduction with 9 mg
- 74.3% reduction with 12 mg
- 40.3% reduction with placebo.
Physical function also improved substantially.
The WOMAC physical-function score fell by:
- 4.1 points with 9 mg
- 4.2 points with 12 mg
- 2.1 points with placebo.
Some Participants Reported No Knee Pain
In an additional post-hoc analysis:
- 14.1% of participants receiving 9 mg
- 12.0% receiving 12 mg
- 4.2% receiving placebo
were reported as completely free of knee pain at 68 weeks.
Post-hoc results deserve more caution than prespecified endpoints because they were not necessarily part of the original primary statistical testing plan.
Still, the result is consistent with the substantial WOMAC improvement seen across the trial.
TRIUMPH-1 Produced Similar Osteoarthritis Findings
TRIUMPH-1 also included a knee osteoarthritis subgroup involving 574 participants.
The average baseline WOMAC pain score was approximately 5.97.
At 80 weeks, reported absolute reductions were:
- placebo: -2.24
- retatrutide 4 mg: -3.66
- retatrutide 9 mg: -4.19
- retatrutide 12 mg: -4.30.
The corresponding reductions at the higher doses were roughly 70% and 73%.
Seeing similar findings across two Phase 3 populations makes the osteoarthritis signal more convincing than relying on one trial alone.
But Is the Osteoarthritis Effect Mostly Weight Loss?
That remains an important question.
In TRIUMPH-4, average body-weight reductions reached:
- 26.4% with 9 mg
- 28.7% with 12 mg
- 2.1% with placebo.
Losing roughly one-quarter or more of body weight dramatically changes the mechanical load placed on a knee.
It would therefore be surprising if weight loss did not explain at least some of the improvement.
Inflammatory and metabolic changes could contribute too.
TRIUMPH-4 reported improvements in high-sensitivity C-reactive protein, or hsCRP, alongside lipid and blood-pressure changes.
But the study cannot cleanly separate:
mechanical unloading
from
reduced inflammation
from
other direct or indirect metabolic effects.
Does Retatrutide Reduce Cardiovascular Risk?
This is where wording matters.
Retatrutide has improved many cardiovascular risk factors:
- body weight
- waist circumference
- blood pressure
- triglycerides
- non-HDL cholesterol
- glucose control
- visceral fat
- inflammatory markers.
But improving cardiovascular risk factors is not the same thing as proving fewer cardiovascular events.
A study specifically designed to answer that question is underway.
TRIUMPH-Outcomes Will Test Hard Cardiovascular and Kidney Outcomes
TRIUMPH-Outcomes is a large Phase 3 cardiovascular and kidney outcomes trial.
ClinicalTrials.gov currently lists approximately 10,000 participants with overweight or obesity plus established atherosclerotic cardiovascular disease and/or chronic kidney disease.
The study is evaluating outcomes including:
- cardiovascular death
- nonfatal myocardial infarction
- nonfatal stroke
- heart-failure hospitalization or urgent visits
- progression of kidney disease
- end-stage kidney disease
- sustained decline in kidney function.
The study began in April 2024 and currently has an estimated primary completion date in February 2029.
Until those results are available, claims that retatrutide prevents cardiovascular events would get ahead of the evidence.
Surrogate Markers vs. Clinical Outcomes
This distinction applies throughout medical research.
A surrogate marker is a measurable variable associated with disease risk.
Examples include:
- blood pressure
- LDL or non-HDL cholesterol
- triglycerides
- A1C
- hsCRP.
A clinical outcome is an event that directly matters to patients, such as:
- heart attack
- stroke
- hospitalization
- kidney failure
- joint replacement
- death.
Surrogate improvements are useful and often biologically meaningful.
But they do not automatically guarantee improvements in every downstream clinical outcome.
Evidence Quality Is Still Mixed Across These Results
As of September 2026, not every result discussed here has the same publication status.
Some retatrutide evidence has been published in full peer-reviewed journals.
Other Phase 3 findings, particularly several TRIUMPH analyses, have been presented at scientific meetings or reported by Eli Lilly while complete peer-reviewed manuscripts are still pending.
That does not mean the findings should be ignored.
It means they should be described accurately as company-reported or conference-presented Phase 3 results until the full publications are available.
The Bigger Picture
The emerging retatrutide program illustrates a shift in obesity research.
Researchers are increasingly looking beyond percentage weight loss.
The questions now include:
- Does sleep apnea improve?
- Does knee pain improve?
- Can people function better?
- Does blood pressure fall?
- Does liver fat decrease?
- Do lipid profiles improve?
- Do heart attacks and strokes eventually become less common?
- Does kidney disease progress more slowly?
Those are more important questions than simply asking how many kilograms someone lost.
Conclusion
Retatrutide’s clinical effects extend well beyond body weight.
Phase 2 and Phase 3 studies have reported substantial improvements in blood pressure, triglycerides, non-HDL cholesterol, waist circumference, obstructive sleep apnea severity, knee osteoarthritis pain, and physical function.
The results are promising, but the mechanism is not always clear.
A large portion of these benefits may result from the extraordinary amount of body weight and visceral fat being lost. Other effects may reflect improved insulin sensitivity, lower liver fat, altered lipid metabolism, reduced inflammation, or direct consequences of retatrutide’s GIP, GLP-1, and glucagon receptor activity.
And there is still a major unanswered question.
We know many cardiovascular risk factors improve.
We do not yet know whether retatrutide reduces major cardiovascular and kidney events over the long term.
TRIUMPH-Outcomes is designed to answer that question, but results are not expected until later in the decade.
Retatrutide remains investigational and has not yet been approved for medical use.
References
Jastreboff AM, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity: A Phase 2 Trial. New England Journal of Medicine. 2023. Read the study
Eli Lilly and Company. TRIUMPH-1 Phase 3 results, including cardiometabolic, osteoarthritis, and obstructive sleep apnea outcomes. June 2026. Read the Phase 3 results
Eli Lilly and Company. TRIUMPH-4 Phase 3 knee osteoarthritis results. December 2025. Read the TRIUMPH-4 results
ClinicalTrials.gov. TRIUMPH-Outcomes, NCT06383390. View the clinical trial record