Visceral Fat and Adiponectin: Associations with Insulin Resistance Are Tissue-Specific in Women

Abstract

Body fatness and its distribution are strongly and independently associated with peripheral insulin action. However, these associations are limited in their ability to predict the independent nature of hepatic and peripheral insulin resistance, especially in obese women. To define the relationships more precisely between regional fat distribution and adiponectin, and hepatic and peripheral insulin resistance, we studied 22 obese (43 +/- 0.1%) women who underwent a dual-energy X-ray absorptiometry scan and a computed tomography scan at the L4-L5 level. An octreotide (60 ng x kg(-1) x min(-1)), glucagon (0.65 ng x kg(-1) x min(-1)), and two-step insulin (0.25 mU x kg(-1) x min(-1) and 1.0 mU x kg(-1) x min(-1)) infusion was performed to quantify insulin-mediated suppression of hepatic glucose production (SGP) and insulin-stimulated glucose disposal (ISGD) in a simultaneous fashion. Hepatic glucose production (HGP) was measured using a primed, constant infusion of [6,6(2)H(2)] glucose. Mean plasma insulin increased from 5.6 +/- 0.1 microU/mL at baseline to 15.1 +/- 1.5 microU/mL in the first stage, and to 80.7 +/- 0.5 microU/mL in the second stage. Although there was no significant relationship between visceral adipose tissue (VAT) and basal HGP (r = 0.34, p = 0.117), there was a significant inverse correlation (r = -0.67, p = 0.003) between VAT and SGP. There was a significant correlation (r = 0.55, p = 0.008) between adiponectin and ISGD. In conclusion, these data support: (1) the inability of basal glucose metabolism to accurately reflect hepatic insulin resistance, (2) the deleterious role of VAT in the development of insulin resistance in the liver, and (3) provide additional support for the positive influence of adiponectin against peripheral insulin resistance in obese, postmenopausal women.