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 HDL₂ 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/m²), 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/m²) 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/[µU/ml] × 10^-4 and 0.8 ± 0.2 min^-1 × 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.

Key words

Lower-Body Obesity - Insulin Resistance - Minimal Model - Randle Cycle - Cardiovascular Risk