A new pilot study suggested that excess body fat may compromise bone strength in patients with autoimmune diabetes, even when standard measures such as bone mineral density appear normal or improved.
In the cross-sectional analysis, researchers evaluated 103 adult patients with autoimmune diabetes (AD), comparing individuals with normal weight with those with overweight. They used dual X-ray absorptiometry to assess body composition, bone mineral density (BMD), and advanced indicators of bone geometry and strength at multiple femur sites.
The findings highlighted a complex relationship between adiposity and skeletal health. While the participants with overweight generally had higher BMD, the researchers found that fat mass itself was associated with poorer bone quality.
Specifically, the total fat percentage was negatively associated with markers of bone strength and geometry at different femur sites, including measures such as cross-sectional moment of inertia and section modulus at the intertrochanteric site; cross-sectional moment of inertia and section modulus at the femur shaft site; and the cross-sectional moment of inertia, buckling ratio, and section modulus at the narrow neck site. These parameters reflected the bone’s ability to withstand bending and torsion, suggesting that higher fat mass may weaken structural integrity despite higher density.
“Total [fat percentage] and [visceral adipose tissue] mass were not significantly associated with BMD at any site,” reported lead study author Renata Risi, of the Department of Experimental Medicine at the Sapienza University of Rome, and colleagues, underscoring a key limitation of relying solely on BMD to evaluate fracture risk in this population.
Visceral adipose tissue also emerged as an independent risk factor. According to the study authors, “[v]isceral adipose tissue emerged as a negative independent predictor” of certain stability measures, including the buckling ratio at critical hip regions.
The findings aligned with growing evidence that central fat distribution may have metabolically harmful effects beyond overall body weight. In contrast, lean mass showed protective associations. Higher lean mass percentage was positively linked to trabecular bone scores, cross-sectional moment of inertia, cross-sectional area, and section modulus at the intertrochanteric and femur shaft sites, reinforcing the role of muscle in supporting skeletal health.
The study authors concluded that “excess fat mass, including visceral adiposity, is independently associated with impaired hip bone strength and geometry,” even after adjusting for confounders such as age, sex, glycemic control, and physical activity.
Notably, the study also confirmed that traditional risk factors, such as older age and female sex, remained associated with poorer bone outcomes in AD.
The findings could contribute to a growing body of literature challenging what is known as the “obesity paradox,” in which higher body weight appears to be protective based on BMD alone. Instead, the data suggested that body composition may be a more meaningful determinant of bone health.
Although limited by its cross-sectional design and relatively small sample size, the study provided early evidence that clinicians should consider more comprehensive assessments of bone quality in patients with AD, especially those with overweight or obesity.
The study authors reported no conflicts of interest.
