MRI has revealed that shape changes in the buttocks may be an indicator of type 2 diabetes, and that these changes differ between women and men, according to the findings were presented in December, 2025 at the annual meeting of the Radiological Society of North America (RSNA) in Chicago..
The finding is from a study that used 61,290 MRI exams housed in the UK Biobank database to create detailed 3D anatomical models of the gluteus maximus and then explored how variables such as aging, lifestyle, frailty, osteoporosis, and type 2 diabetes were associated with changes in its shape.
The study suggested that the shape of the muscle, rather than the size, may “reflect underlying metabolic differences,” a press release stated.
Unlike previous studies looking at muscle size or fat, the 3D imaging identified exactly where the muscle changes occur, according to the researchers.
As one of the largest muscles in the human body, the gluteus maximus “plays a key role” in metabolic health, according to lead study author E. Louise Thomas, Ph.D., professor of metabolic imaging at the University of Westminster’s School of Life Sciences.
The data also included the participants’ physical measurements, demographics, disease biomarkers, medical history and lifestyle habits. The researchers studied how these variables were linked to muscle shape over time.
“People with higher fitness, as measured by vigorous physical activity and hand grip strength, had a greater gluteus maximus shape, while aging, frailty and long sitting times were linked to muscle thinning,” study co-author Marjola Thanaj, Ph.D., a senior research fellow at the University of Westminster’s Research Centre for Optimal Health, said in the release.
The researchers concluded that butt shape changes may indicate an “early functional decline” and “metabolic compromise” in type 2 diabetes patients.
Men with type 2 diabetes showed muscle shrinkage, while women displayed enlarged muscle, likely due to “infiltration of fat” within it, according to the researchers.
These results suggest that men and women have “very different biological responses to the same disease,” Thanaj suggested.
Men who were categorized as “frail” were recognized as having more “general shrinkage” across the gluteus maximus, but women experienced a “limited” frailty effect.
