The Nonlinear Relationship Between Psoas Cross-sectional Area and BMI: A New Observation and Its Insights Into Diabetes Remission After Roux-en-Y Gastric Bypass

OBJECTIVE: To explore the potential relevance of muscle mass as a variable contributor to BMI in limitations on BMI-based predictions of diabetes remission (DR) after Roux-en-Y gastric bypass (RYGB). RESEARCH DESIGN AND METHODS: We evaluated the relationship between muscle mass and BMI in 501 patients with type 2 diabetes mellitus and overweight or obesity, of whom 186 patients who underwent RYGB were studied for determination of the role of baseline muscle mass and BMI in predicting DR. Muscle mass was assessed by estimated fat-free mass index (eFFMI) and psoas cross-sectional area (CSA). RESULTS: A nonlinear relationship existed between psoas CSA and BMI, whereas psoas CSA showed a highly positive correlation with eFFMI. Baseline psoas CSA and eFFMI were better than BMI for predicting 1- and 5-year DR. CONCLUSIONS: The nonlinear relationship between muscle mass and BMI may partially contribute to BMI limitations in predicting DR after RYGB.