Fat Mass Influences Femur Bone Strength and Geometry Parameters, but Not Bone Mineral Density, in Autoimmune Diabetes: A Pilot Study.

Total fat percentage was negatively associated with multiple markers of bone strength and geometry at different femur sites after adjustment for confounders.

• Negative associations were found between total fat% and cross-sectional moment of inertia (CSMI) and section modulus (Z) at the intertrochanteric (IT) site
• Negative associations were also found at the femur shaft (FS) site for cross-sectional area (CSA), CSMI, and Z
• At the narrow neck (NN) site, total fat% was negatively associated with CSMI, buckling ratio (BR), and Z
• Adjustments were made for age, sex, BMI, HbA1c%, lean mass %, and physical activity
• These associations were observed despite no significant association between fat mass and bone mineral density (BMD)

Visceral adipose tissue was a negative independent predictor of buckling ratio at both the intertrochanteric and narrow neck femur sites.

• Visceral adipose tissue (VAT) emerged as a negative independent predictor of buckling ratio (BR) at the IT site
• VAT was also a negative independent predictor of BR at the NN site
• This finding suggests visceral fat specifically contributes to impaired bone structural integrity beyond total fat mass
• The study used DXA-derived measures to assess visceral adipose tissue

Lean mass percentage was positively associated with trabecular bone score and multiple bone geometry parameters at the intertrochanteric and femur shaft sites.

• Lean mass % was positively associated with trabecular bone score (TBS)
• Positive associations were found between lean mass % and CSA, CSMI, and Z at the IT site
• Positive associations were also found between lean mass % and CSA, CSMI, and Z at the FS site
• These findings suggest lean mass has a protective effect on bone health parameters in autoimmune diabetes

Female sex and age were identified as negative predictors of bone health in adults with autoimmune diabetes.

• Female sex was a negative predictor of bone health parameters in multilinear regression models
• Age was also identified as a negative predictor of bone health
• These associations were maintained after adjustment for BMI, HbA1c%, lean mass %, and physical activity

The study compared 52 normal weight adults with autoimmune diabetes to 51 adults with autoimmune diabetes and overweight using DXA-derived bone parameters.

• Total sample consisted of 103 adults with autoimmune diabetes
• 52 participants were classified as normal weight and 51 as overweight
• DXA was used to assess body mass composition, BMD, trabecular bone score (TBS), and hip structural analysis (HSA)-derived parameters
• HSA parameters were assessed at three femur sites: narrow neck (NN), intertrochanteric (IT), and femur shaft (FS)
• This was described as a pilot study

Excess fat mass was associated with impaired hip bone strength and geometry despite not being associated with reduced bone mineral density in adults with autoimmune diabetes.

• BMD was not significantly associated with fat mass percentage in the adjusted models
• Overweight was noted to increase BMD despite worsening bone health
• The dissociation between BMD and bone geometry/strength parameters highlights the limitation of using BMD alone to evaluate bone health in this population
• The findings emphasize that adiposity has negative skeletal effects not captured by standard BMD measurement