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- Title
Insulin Resistance of Aging: The Roles of Body Fat Distribution and Physical Fitness.
- Authors
Pennant, Marjorie A.; Azuma, Koichiro; Dube, John J.; Amati, Francesca; Toledo, Frederico S.; Rossi, Andrea; Kelley, David E.; Goodpaster, Bret H.
- Abstract
Although elderly adults have a higher incidence of Type 2 diabetes mellitus, it is not clear whether or not they are more insulin resistant (IR) than younger men and women. The purpose of this study was to compare IR in older and younger men and women, and to determine the extent to which ectopic fat, e.g. abdominal visceral adipose tissue (VAT) and muscle fat as well as physical fitness are associated with IR of aging. Sixty younger (Y; 38.7 ± 0.6 years) men (n=27) and women (n=33) and 58 older (O; 66.8 ± 0.6 years) men (n=21) and women (n=37) participated. All subjects were overweight to obese (BMI = 32.6 ± 0.33 kg/m² for all subjects). Insulin sensitivity determined by the hyperinsulinemic (40 mU/m²/min) euglycemic clamp was similar in O and Y (7.21 ± 0.34 vs 6.40 ± 0.33 mg/kg fat free mass/min). This was despite O having higher %body fat (42 ± 1 vs 37 ± 1%) determined by dual-energy X-ray absorptiometry (DEXA) and computed tomography (CT)-derived VAT (221 ± 11 vs 157 ± 9 cm²), and lower physical fitness (VO[sub 2]max = 33.6 ± 0.7 vs 38.9 ± 0.7 ml/kg fat free mass/min). O women were more insulin sensitive than O men (P<0.05). This gender difference was not observed in Y. In bivariate and multivariate analyses, higher VAT was consistently associated with IR in both O and Y, and in both men and women. In addition, the amount of low-density muscle on CT, reflective of muscle with higher fat content, was related to IR, after accounting for VAT. In contrast, higher subcutaneous adipose tissue in the thigh was associated with higher insulin sensitivity in O (r=0.40, P<0.05). In conclusion, the age-associated patterns of body fat distribution, but not aging per se, are associated with insulin resistance. ADA-Funded Research
- Subjects
INSULIN resistance; AGING; ADIPOSE tissues; PHYSICAL fitness; TYPE 2 diabetes; OVERWEIGHT persons
- Publication
Diabetes, 2007, Vol 56, pA385
- ISSN
0012-1797
- Publication type
Article