CONTRIBUTION OF VISCERAL FAT MASS TO THE INSULIN-RESISTANCE OF AGING

Recent studies have shown that central obesity (increased waist to hip ratio [WHR]) is related to insulin resistance and aging. Furthermore, in central obesity states, the intraabdominal fat (IAF) depot has bee n postulated to contribute most to the development of insulin resistan ce. Therefore, the observed insulin resistance of aging may be related more to changes in body composition than to aging per se. The purpose of this study was to explore the association of IAF with age and insu lin sensitivity (S-I) after controlling for obesity. We examined 60 he althy nondiabetic subjects (normal 75-g oral glucose tolerance test, a ged 23 to 83, 15 men and 45 women). We chose subjects so that those le ss than or equal to 125% and greater than 125% of ideal body weight we re equally represented in each age decade. We quantified total and sub cutaneous abdominal fat and IAF at the umbilicus using a validated mag netic resonance imaging (MRI) scanning technique and determined S-I us ing a modified minimal model. IAF correlated significantly with age (r = .49, P = .0001) in the group as a whole, as well as in men (r = .58 , P = .022) and women (r = .48, P = .0008) separately. In all subjects , S-I was significantly related to IAF (r = -.50, P < .0001) but was n ot related to age (r = .00, P = .98). In multivariate analysis for var ious combinations of age, sex, and measures of fat distribution, WHR a ccounted for 28% and IAF for 51% of the variance in S-I, whereas age, sex, and interactions of age and sex accounted for only 1%. In conclus ion, IAF mass, which has been postulated to be the most metabolically active of the adipose depots, correlates significantly with insulin re sistance and age in healthy nondiabetic individuals regardless of gend er and after controlling for obesity. Copyright (C) 1995 by W.B. Saund ers Company