Insulin and bone health in young adults: The mediator role of lean mass.
BACKGROUND
The positive relationship between lean mass (LM) and bone health is well known, but a positive association between insulin and LM has also been described. Insulin has some anabolic properties on bone through the stimulation of osteoblast differentiation, yet the role of LM as a confounder or mediator in this relationship remains uncertain.


OBJECTIVE
To examine whether the association between insulin levels and bone health is mediated by LM.


METHODS
A cross-sectional study was conducted at the Castilla La Mancha University (Spain) involving 466 young adults (113 young men; 19.5±2.3 years). LM and total-body bone mineral content (BMC) were measured by dual energy x-ray absorptiometry, and insulin was measured in fasting serum samples.


RESULTS
Young adults with high total LM had higher values of total-body BMC than their peers after controlling for age and sex, this relationship persisted after adjusting for insulin levels (p<0.001). In mediation analyses, insulin levels were positively associated with total-body BMC (b = 0.05; p<0.001) and total LM acted as an intermediate variable, attenuating the association between insulin levels and total-body BMC (b = -31.98; p>0.05) as indicated by Sobel test values for indirect effect (z = 4.43; p<0.001).


CONCLUSIONS
LM plays an important role in the relationship between insulin levels and bone health, in such a way that while increases in LM have a positive influence on bone health, they are also negatively associated with insulin levels.
Universidad de Castilla-La Mancha. School of Nursing and Physiotherapy, Toledo, Spain.
Ana
http://orcid.org/0000-0001-8961-3169
A
Torres-Costoso
Universidad de Castilla-La Mancha. Health and Social Research Center, Cuenca, Spain.
Diana P
DP
Pozuelo-Carrascosa
Universidad de Castilla-La Mancha. Health and Social Research Center, Cuenca, Spain.
Celia
C
Álvarez-Bueno
Universidad de Castilla-La Mancha. School of Nursing and Physiotherapy, Toledo, Spain.
Asunción
A
Ferri-Morales
Universidad de Castilla-La Mancha. Health and Social Research Center, Cuenca, Spain.
Jose
J
Miota Ibarra
Universidad de Castilla-La Mancha. Health and Social Research Center, Cuenca, Spain.
Blanca
B
Notario-Pacheco
Universidad de Castilla-La Mancha. Health and Social Research Center, Cuenca, Spain.|Universidad Autónoma de Chile. Facultad de Ciencias de la Salud., Talca, Chile.
Vicente
V
Martínez-Vizcaíno
D015502:Absorptiometry, Photon; D000293:Adolescent; D001823:Body Composition; D015992:Body Mass Index; D015519:Bone Density; D001842:Bone and Bones / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood*; D008297:Male; D055815:Young Adult
D007328:Insulin