Repeat whole-body MRI in the German National Cohort was used to compare tissue volumes in 58 adults with diabetes who initiated a GLP-1 receptor agonist between scans with 130 controls matched on sex, age, BMI and scan interval. Muscle volume declined 2.75 percentage points more in initiators (95% CI -4.51 to -0.99), alongside 2.54 percentage points greater weight loss, while adipose tissue differences were not statistically significant. The authors describe this as roughly 60% more muscle loss in initiators.
Why it is interesting: Body-composition evidence on GLP-1 use outside trials, measured by imaging rather than weight, though on only 58 exposed people.