Original Article
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World J Diabetes. Apr 15, 2013; 4(2): 31-39
Published online Apr 15, 2013. doi: 10.4239/wjd.v4.i2.31
Negative association between trunk fat, insulin resistance and skeleton in obese women
Emanuela A Greco, Davide Francomano, Rachele Fornari, Chiara Marocco, Carla Lubrano, Vincenza Papa, Francesca Wannenes, Luigi Di Luigi, Lorenzo M Donini, Andrea Lenzi, Antonio Aversa, Silvia Migliaccio
Emanuela A Greco, Davide Francomano, Rachele Fornari, Chiara Marocco, Carla Lubrano, Lorenzo M Donini, Andrea Lenzi, Silvia Migliaccio, Antonio Avers, Department of Experimental Medicine, Section of Medical Pathophysiology, Endocrinology and Nutrition, University “Sapienza” of Rome, 00195 Rome, Italy
Vincenza Papa, Francesca Wannenes, Luigi Di Luigi, Silvia Migliaccio, Unit of Endocrinology, Department of Health Sciences, University “Foro Italico” of Rome, 00195 Rome, Italy
Author contributions: Greco EA and Migliaccio S performed the conception and design; Fornari R, Marocco C, Papa V and Wannenes F acquired the data; Greco EA, Francomano D, Aversa A and Migliaccio S were involved in analysis and interpretation of data; Greco EA, Aversa A and Migliaccio S drafted the article; Greco EA, Lubrano C, Di Luigi L, Donini LM, Lenzi A, Aversa A and Migliaccio S revised critically for important intellectual content; all the authors contributed to final approval of the version to be published.
Correspondence to: Silvia Migliaccio, MD, PhD, Endocrinology Unit, Department of Movement, Human and Health Sciences, University Foro Italico, Largo Lauro De Bosis 15, 00195 Rome, Italy. silvia.migliaccio@uniroma4.it
Telephone: +39-6-36733387 Fax: +39-6-4461450
Received: December 13, 2012
Revised: February 14, 2013
Accepted: March 15, 2013
Published online: April 15, 2013
Processing time: 115 Days and 22.5 Hours
Abstract

AIM: To evaluate the potential interference of trunk fat (TF) mass on metabolic and skeletal metabolism.

METHODS: In this cross-sectional study, 340 obese women (mean age: 44.8 ± 14 years; body mass index: 36.0 ± 5.9 kg/m2) were included. Patients were evaluated for serum vitamin D, osteocalcin (OSCA), inflammatory markers, lipids, glucose and insulin (homeostasis model assessment of insulin resistance, HOMA-IR) levels, and hormones profile. Moreover, all patients underwent measurements of bone mineral density (BMD; at lumbar and hip site) and body composition (lean mass, total and trunk fat mass) by dual-energy X-ray absorptiometry.

RESULTS: Data showed that: (1) high TF mass was inversely correlated with low BMD both at lumbar (P < 0.001) and hip (P < 0.01) sites and with serum vitamin D (P < 0.0005), OSCA (P < 0.0001) and insulin-like growth factor-1 (IGF-1; P < 0.0001) levels; (2) a positive correlation was found between TF and HOMA-IR (P < 0.01), fibrinogen (P < 0.0001) and erythrocyte sedimentation rate (P < 0.0001); (3) vitamin D levels were directly correlated with IGF-1 (P < 0.0005), lumbar (P < 0.006) and hip (P < 0.01) BMD; and (4) inversely with HOMA-IR (P < 0.001) and fibrinogen (P < 0.0005).Multivariate analysis demonstrated that only vitamin D was independent of TF variable.

CONCLUSION: In obese women, TF negatively correlates with BMD independently from vitamin D levels. Reduced IGF-1 and increased inflammatory markers might be some important determinants that account for this relationship.

Keywords: Obesity; Skeleton; Vitamin D; Osteocalcin; Insulin resistance; Trunk fat; Inflammation

Core tip: Recent studies have shown that high fat mass content might be a risk factor for osteoporosis and fragility fractures. We evaluated obese women for vitamin D, osteocalcin, inflammatory markers, metabolic and hormones profile, bone mineral density (BMD) and body composition by dual-energy X-ray absorptiometry. Our results show that in obese women trunk fat negatively correlates with BMD independently from vitamin D levels, likely as consequence of reduced insulin-like growth factor-1 and increased inflammatory markers. These data indicate that obesity cannot be considered a protective factor for osteoporosis and suggest that obese postmenopausal women should be investigated for possible alterations of skeletal metabolism.