Insulin sensitivity measured with the minimal model is higher in moderately overweight women with predominantly lower body fat

Lower-body obesity is associated with a lower incidence of diabetes and high values of HDL, cholesterol and thus seems to have a metabolic profile opposite to upper-body obesity. We measured insulin sensitivity by the minimal model procedure in 20 lower-body overweight women (age 40.3 +/- 2.3 years, waist-to-hip ratio WHR 0.75+/-0.01, body mass index BMI 29.9+/-0.7 kg/m(2)), compared to 18 women with a similar degree of upper-body obesity (age 40.4+/-3 years, WHR 0.91+/-0.02, BMI 29.4+/-0.7 kg/m(2)) and 28 control women matched for age and height. Insulin sensitivity and basal insulin effect were higher in lower-body obesity (11.2+/-0.2 min(-1)/[mu U/ml] x 10(-4) and 0.8+/-0.2 min(-1) x 10(-2), respectively) compared to upper-body obesity (2.6+/-0.4, p < 0.001 and 0.3+/-0.05, p < 0.01) and controls (6.1+/-0.7, p < 0.02 and 0.5 +/- 0.07, p < 0.02). It is suggested that lower-body obesity could be associated with a reduced free fatty acids-induced inhibition of insulin action by the Randle mechanism. This study confirms that body fat distribution is a more relevant determinant than obesity itself in the pathogenesis of insulin resistance. Contrary to upper-body obesity, moderate lower-body overweight seems to be associated with high values on insulin sensitivity.