The Contribution of Visceral Adiposity and Mid-Thigh Fat-Rich Muscle to the Metabolic Profile in Postmenopausal Women

This study explored the relationship between muscle fat infiltration derived from mid-thigh computed tomography (CT) scan, central fat distribution and insulin sensitivity in postmenopausal women. Mid-thigh CT scans were used to measure low attenuation muscle surface ( LAMS) (0-34 Hounsfield units (HU)), which represented a specific component of fat-rich muscle. Whole- body insulin sensitivity (M/I) was evaluated by an euglycemic-hyperinsulinemic clamp. A group of 103 women aged 57.0 +/- 4.4 years was studied. Women with higher levels of LAMS presented higher metabolic risk features, particularly elevated fasting, 2-h plasma glucose (2hPG) concentrations and diminished M/I (P < 0.05). To further study the contribution of muscle fat infiltration and central adiposity on metabolic parameters, we divided the whole group based on the median of LAMS and visceral adipose tissue ( VAT). As expected, the best metabolic profile was found in the Low-LAMS/Low-VAT group and the worst in the High-LAMS/High-VAT group. Women with Low-LAMS/High-VAT presented similar metabolic risks to those with High-LAMS/High-VAT. There was no difference between High-LAMS/Low-VAT and Low-LAMS/Low-VAT, which presents the most healthy metabolic and glycemic profiles as reflected by the lowest levels of cardiovascular disease risk variables. This suggests that High-LAMS/Low-VAT is also at low risk of metabolic deteriorations and that High-LAMS, only in the presence of High-VAT seems associated with deteriorated risks. Although increased mid-thigh fat-rich muscle was related to a deteriorated metabolic profile, VAT appears as a more important contributor to alterations in the metabolic profile in postmenopausal women.