Aim: We investigated the relationship between insulin sensitivity and the graded increase in the number of features of the metabolic syndrome in a cross-sectional sample of obese postmenopausal women. We hypothesized that insulin sensitivity would deteriorate with an increased number of metabolic syndrome phenotypes.
Methods: Insulin sensitivity was measured in 75 obese postmenopausal women (age: 57.3 +/- 5.3 years; BMI: 32.8 +/- 4.5 kg/m2) by using both the hyperinsulinaemic-euglycaemic clamp and the homeostasis model assessment (HOMA-IR). Features of the metabolic syndrome included visceral fat (>130 cm2), HDL-cholesterol (<1.29 mmol/l), fasting triglycerides (> or =1.7 mmol/l), blood pressure (> or =130/> or =85 mmHg) and fasting glucose (> or =6.1 mmol/l). Participants were classified into three categories based on the presence of metabolic syndrome phenotypes: 0-1 vs. 2 vs. > or =3 features of the metabolic syndrome.
Results: We found that insulin sensitivity decreased in a graded fashion (12.19 +/- 3.2 vs. 11.80 +/- 2.3 vs. 9.29 +/- 2.6 mg/min/FFM) and HOMA-IR increased in a similar manner (2.95 +/- 1.1 vs. 3.28 +/- 1.3 vs. 4.65 +/- 2.2), as the number of features of the metabolic syndrome increased from 0-1 to > or =3. When insulin sensitivity was statistically adjusted for visceral fat (as measured by computed tomography) and plasma triglycerides, the differences among groups were abolished.
Conclusions: These findings suggest that a decreased insulin sensitivity is associated with increased features of the metabolic syndrome in obese postmenopausal women and that visceral fat as well as plasma triglyceride accumulation might be potential mediators of this relationship.