Objectives Fat distribution is an important variable explaining metabolic heterogeneity of obesity. Abdominal subcutaneous adipose tissue (SAT) is divided by the Scarpa’s fascia into a deep (dSAT) and a superficial (sSAT) layer. This study sought to characterize functional differences between the two SAT layers to explore their relative contribution to metabolic traits and cardiovascular risk profile.
Research design and Methods We recruited 271 Caucasians consecutively from a local random and population-based screening project in Oxford and 25 Asian Indians from the local community. The depth of the SAT layers was determined by ultrasound and adipose tissue biopsies were performed under ultrasound guidance in a subgroup of 43 Caucasians. Visceral adipose tissue mass was quantified by DEXA scan.
Results Male adiposity in both ethnic groups was characterized by a disproportionate expansion of dSAT which was strongly correlated with visceral adipose tissue mass. dSAT depth was a strong predictor of global insulin resistance (HOMA-IR), liver-specific IR (Insulin-like growth factor binding protein-1) and Framingham Risk Score independently of other measures of adiposity in men. Moreover, dSAT had higher expression of proinflammatory, lipogenic and lipolytic genes and contained higher proportions of saturated FAs. There was increased proportion of small adipocytes in dSAT.
Conclusions SAT is heterogeneous; dSAT expands disproportionally more than sSAT with increasing obesity in Caucasian males (confirmed also in Asian Indians). Its expansion is related to increased cardiovascular risk independently of other adiposity measures and it has biological properties suggestive of higher metabolic activity contributing to global IR.
- Received June 6, 2013.
- Accepted October 21, 2013.
- © 2013 by the American Diabetes Association.
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