No difference in insulin sensitivity between healthy postmenopausal women with or without sarcopenia: a pilot study.

Insulin plays a pivotal role in skeletal muscle protein metabolism and its action decreases with age. A loss of muscle mass, termed sarcopenia, also occurs with age. The age-associated decline in insulin sensitivity (IS) may negatively alter muscle protein metabolism and, therefore, be implicated in the aetiology of sarcopenia. However, no studies have yet compared the level of IS between older individuals with or without sarcopenia. Thus, in this study, we compared the IS of 20 class I sarcopenics (CIS), 8 class II sarcopeniscs (CIIS), and 16 non-sarcopenics (NS), among a group of otherwise healthy, non-obese, postmenopausal women. IS was estimated with the quantitative IS check index (QUICKI). Muscle mass index (MMI), which was used to determine sarcopenia, was calculated as follows: (appendicular muscle massx1.19)-1.01/h2, where h=height. Fat-free mass (FFM), fat mass (FM), and trunk FM (TFM) were measured by dual-energy X-ray absorptiometry. Accelerometry and indirect calorimetry were used to estimate resting (REE), daily (DEE), and physical activity (PAEE) energy expenditure. A 3 d food record was used to determine total energy, protein (animal and vegetal), and carbohydrate intakes. As expected, MMI and FFM differed significantly among groups. However, no significant differences were found among groups for IS, FM, TFM, REE, DEE, PAEE, or total energy, protein (both animal and vegetable), and carbohydrate intakes. Using QUICKI, a surrogate measure of IS, the present results suggest that the action of insulin does not play an important role in the development and maintenance of sarcopenia in healthy, non-obese, postmenopausal women.