Relationship of body fat distribution by waist circumference, dual-energy X-ray absorptiometry and ultrasonography to insulin resistance by homeostasis model assessment and lipid profile in obese and non-obese postmenopausal women

Abstract

Objective. To correlate body fat distribution evaluated by waist circumference, dual-energy X-ray absorptiometry and ultrasonography to insulin resistance and lipid profile in obese and non-obese postmenopausal women.

Methods. We studied 40 obese and 47 non-obese postmenopausal women, assessing obesity by measuring waist circumference and fat tissue using dual-energy X-ray absorptiometry and ultrasonography, and examining their correlation with metabolic parameters: insulin resistance as determined by the homeostasis model assessment technique (HOMA-IR) and lipid profile including triglycerides (TG), total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), very-low-density lipoprotein, lipoprotein(a) (Lp(a)) and apoplipoprotein A-I (Apo A-I).

Results. There was no difference in lipid profile between the two groups. Insulin resistance was the metabolic disturbance of highest prevalence in the obese group, evaluated by HOMA-IR (obese: 3.38 ± 2.2; non-obese: 1.20 ± 0.7; p < 0.001). Obesity was not a confounding factor in linear regression analyses among HOMA-IR, HDL-C, TG, Lp(a), Apo A-I and the methods used to measure body fat distribution. Waist circumference was the method that best explained HOMA-IR (R² = 34.9%, p < 0.001) and TG concentration (R² = 10.9%, p = 0.002). HDL-C presented a positive association with subcutaneous fat evaluated by ultrasonography (R² = 12.5%, p < 0.001). Obesity was a confounding factor in multiple regression analyses between TC and LDL-C, when related to abdominal fat evaluated by ultrasonography, and resulted in a positive association among the obese and a negative association among the non-obese women. The sensibility of this method was related to the quantity of fat in the visceral region.

Conclusions. Waist circumference showed the highest association with insulin resistance. Fat distribution evaluated by dual-energy X-ray absorptiometry and ultrasound was also associated with insulin resistance, but with lower intensity. The relationship of visceral fat distribution evaluated by ultrasound to TC cholesterol and LDL-C showed opposed results between obese and non-obese menopausal women.

Keywords:

• Postmenopause
• obesity
• anthropometry
• densitometry
• insulin resistance