GLP-1 Evidence

Not medical advice. A record of published research and our assessments of it. The limits

Effects of retatrutide on body composition in people with type 2 diabetes: a substudy of a phase 2, double-blind, parallel-group, placebo-controlled, randomised trial

Design
Randomized trial · 189 participants · Intermediate outcome
Match to healthy normal-weight adults aged 55–75
Different population[Auto] Participants had type 2 diabetes and obesity/overweight (age range 18-75; BMI ≥25 required).
Could weight loss explain it?
Possibly[Auto] Participants had obesity and/or type 2 diabetes and the abstract does not separate direct drug effects from weight loss or glycaemic improvement.
Study tier
Study tier 2[Auto] Randomized trial of moderate size; outcome type and follow-up limit certainty (auto-provisional).
Assessment
Version 3 · Checked against the source by AI · Oct 19, 2026

Study facts come from the paper. Population match, weight-loss explanation and study tier are our judgments, made against the reference group of healthy normal-weight adults aged 55–75.

In adults with type 2 diabetes, retatrutide 4, 8 and 12 mg reduced total body fat about 11 to 22 percentage points more than placebo over 36 weeks; the 0.5 mg dose did not differ from placebo. The abstract gives no lean-mass figures, so the authors' reassurance about lean mass cannot be checked here. Only 103 of the 189 substudy participants completed treatment with both body scans. Adverse events were similar between groups.

01Findings

What the study reported

Drugs
Dulaglutide, Retatrutide
Dose
0.5, 4, 8 or 12 mg once weekly (dulaglutide 1.5 mg arm)
Route
subcutaneous
Comparator
placebo; dulaglutide 1.5 mg
Primary outcome
Not extracted
Effect
Not extracted
95% confidence interval
Not extracted
Follow-up
36 weeks
Adverse events
Adverse events similar between groups; gastrointestinal events most frequent; no deaths.
Limitations
Not extracted

Who was studied

Age range
18-75
Age min
18
Bmi min
25
Obesity status
obesity/overweight present (all or most)
Diabetes status
type 2 diabetes present (all or most)
Sample size
189

Study quality details

Study design
Randomized controlled trial
Sample size
189
Randomization
yes
Blinding
double-blind
Comparator
placebo; dulaglutide 1.5 mg
Follow up duration
36 weeks
Outcome type
intermediate
Replication
not assessed (auto)
Consistency with other evidence
not assessed (auto)
Population applicability
INDIRECT
Statistical precision
CI reported: 95% CI -4·0 to 3·2, p=0·83 with retatrutide 0·5 mg, -10·7 (-17·2 t
Risk of bias
not assessed (auto)
Funding conflicts
yes
Peer review status
yes

Methodological notes

Sample size 189 is the number enrolled in the body-composition substudy; 155 had a baseline DXA scan and 103 completed treatment with both baseline and week-36 DXA scans.

02Funding

Funding and conflicts

Funding
The study was funded by Eli Lilly and Company
Industry funded
Yes
Manufacturer
Eli Lilly, Lilly
Sponsor role
manufacturer funded the study (sponsor role in design/analysis not stated in abstract)
Author conflicts
Declaration of interests TC, QW, NCS, AH, ZM, CK, and CH are employees and shareholders of Eli Lilly and Company.
Independent replication
unknown
Notes
Authors declare relationships with the drug's manufacturer: Eli Lilly, Eli Lilly

Funding is shown on every study and never used to score it.

04Source

The source, as retrieved

Abstract

[BACKGROUND] Retatrutide, a glucose-dependent insulinotropic polypeptide, glucagon-like peptide-1, and glucagon receptor agonist, has demonstrated robust glucose and bodyweight reductions in participants with type 2 diabetes. This substudy assessed percent change from baseline to week 36 in total body fat mass versus placebo and dulaglutide. [METHODS] This phase 2, double-blind, parallel-group, placebo-controlled, randomised controlled trial was done in 42 medical centres in the USA. Eligible participants were adults aged 18-75 years with type 2 diabetes, HbA1c of 7·0-10·5%, stable bodyweight, and BMI of 25-50 kg/m2. Eligible participants were randomly assigned in a 2:2:2:1:1:1:1:2 ratio to once-weekly subcutaneous placebo, dulaglutide 1·5 mg, or retatrutide 0·5 mg, 4 mg (2 mg initial dose), 4 mg (4 mg initial dose), 8 mg (2 mg initial dose), 8 mg (4 mg initial dose), or 12 mg. The prespecified primary substudy endpoint was percent change from baseline to week 36 in total fat mass, as measured by dual-energy X-ray absorptiometry (DXA). Regression methods with on-treatment data before study drug discontinuation from all randomly assigned participants with non-missing DXA scans were included in efficacy analysis. All participants who received at least one dose of study drug were included in the safety analysis population. The completed trial is registered with ClinicalTrials.gov, NCT04867785. [FINDINGS] Between May 13, 2021 and June 13, 2022, 534 participants were screened for inclusion into the main study. 253 were excluded and 281 participants were enrolled and randomly assigned to the main study. Of the main study participants, 189 participants were enrolled to the body composition substudy (29 in the placebo group, 32 in the retatrutide 0·5 mg group, 31 in the retatrutide 4 mg groups [pooled], 33 in the retatrutide 8 mg group [pooled], 30 in the retatrutide 12 mg group, and 34 in the dulaglutide 1·5 mg group). Of these, 155 had a baseline DXA scan and 103 completed treatment and both baseline and week 36 DXA scans. 105 (56%) of 189 participants were female and 84 (44%) were male. 160 (85%) of 189 participants were White, 24 (13%) were Black, and five (3%) were Asian. Percent reduction from baseline in total fat mass was 4·9% (SE 1·4%) with retatrutide 0·5 mg, 15·2% (3·2%) with retatrutide 4 mg (pooled), 26·1% (2·5%) with retatrutide 8 mg (pooled), 23·2% (3·0%) with retatrutide 12 mg, 2·6% (1·6%) with dulaglutide, and 4·5% (1·2%) with placebo. Least squares mean change from baseline in total fat mass compared to placebo was -0·4 (95% CI -4·0 to 3·2, p=0·83 with retatrutide 0·5 mg, -10·7 (-17·2 to -4·2, p=0·0013) with retatrutide 4 mg (pooled), -21·6 (-27·1 to -16·1, p<0·0001) with retatrutide 8 mg (pooled), and -18·7 (-25·1 to -12·3, p<0·0001) with retatrutide 12 mg. Adverse events were similar between groups. Serious adverse events occurred in two (7%) of 29 participants in the placebo group, two (6%) of 32 participants in the retatrutide 0·5 mg group, zero of 31 participants in the retatrutide 4 mg group, three (9%) of 33 participants in the retatrutide 8 mg group, one (3%) of 30 participants in the retatrutide 12 mg group, and zero of 34 participants in the dulaglutide group. Gastrointestinal events were the most frequently reported adverse events, and no deaths were reported. [INTERPRETATION] In adults with type 2 diabetes, retatrutide significantly improved total body fat mass reduction compared with placebo and dulaglutide. The proportion of lean mass loss to weight loss was similar to other obesity treatments. These findings could provide reassurance that a greater proportion of lean mass is not lost with retatrutide despite the overall increased weight loss. [FUNDING] The study was funded by Eli Lilly and Company.

Where this record came from

SourceRetrievedIdentifier
pubmedSep 30, 202640609566
first ingestion