Sarcopenic obesity and insulin resistance: application of novel body composition models

Objectives: Sarcopenic obesity (SO) is characterized by the co-occurrence of high adiposity (HA) and low muscle mass (LM) and has been associated with an increased risk for cardiometabolic diseases. The aim of this study was to investigate the association between markers of insulin sensitivity and SO defined by three novel body composition models: body composition phenotypes; truncal fat mass-to-appendicular skeletal mass (TrFM/ASM) ratio load capacity; and fat mass-to-fat-free mass (FM/FFM) ratio load capacity. Methods: The study included 314 participants 18 to 65 y of age. Body composition was assessed by dual-energy x-ray absorptiometry. The first model includes four phenotypes: low adiposity-high muscle mass (LA-HM), high adiposity-high muscle mass (HA-HM), low adiposity-low muscle mass (LA-LM), and high adiposity-low muscle mass (HA-LM). The second and third load-capacity models stratified participants into three centile groups: <15th, 15th to 84th and ≥85th. A 2-h oral glucose tolerance test was performed and insulin sensitivity was calculated using the Matsuda Index. Glycated hemoglobin and highly sensitive C-reactive protein also were measured. Results: Lower insulin sensitivity was observed in the HA-LM (P < 0.001) and in the ≥85th centile groups of the TrFM/ASM ratio (P < 0.001) and the FM/FFM ratio (P = 0.001) compared with the other body composition phenotypes. The HA-LM and ≥85th centile group of the TrFM/ASM ratio model showed significantly higher (P < 0.001) concentrations of glycated hemoglobin compared with the other phenotypes. Conclusions: SO defined by both the four body composition phenotypes and TrFM/ASM definitions was associated with greater impairment of insulin sensitivity and glycemic control.