Presence of sarcopenia identifies a special group of lean NAFLD in middle-aged and older people

Background Sarcopenia, the age-related loss of muscle mass and function, is closely associated and frequently concomitant with non-alcoholic fatty liver disease (NAFLD). We aimed to investigate the clinical features of the sarcopenic NAFLD patients from middle-aged and older people. Methods A total of 1305 patients with NAFLD from the Shanghai Changfeng Study were included for analysis. Sarcopenia was diagnosed based on the height-adjusted appendicular skeletal muscle mass (ASM/height 2 ). We comprehensively analyzed the metabolic phenotype, carotid artery condition, liver fibrosis score, and serum metabolomic profile of each participant. Results Among the middle-aged and older population, 68.1% of patients with sarcopenia and NAFLD were lean. Sarcopenia was independently associated with increased risk of carotid plaque (OR, 2.22; 95%CI 1.23–4.02) and liver fibrosis (OR, 2.07; 95%CI 1.24–3.44), and the sarcopenic lean NAFLD patients were characterized by a higher risk of carotid plaque ( p = 0.008) and liver fibrosis ( p = 0.001) than the non-sarcopenic lean NAFLD patients, despite their lower BMI and similar prevalence of metabolic syndrome and diabetes. Further serum metabolomic examination indicated that the sarcopenic lean NAFLD patients presented a distinct metabolomic profile prone to carotid plaque and liver fibrosis, with upregulated serum valine, N-acetylneuraminyl-glycoproteins, lactic acid, small LDL triglycerides and VLDL5 components, and reduced components of HDL4. A sarcopenic characterization score based on above metabolites was established and could also predict increased risk of carotid plaque and liver fibrosis. Conclusion The presence of sarcopenia identifies a special subgroup of lean NAFLD with increased risk of cardiovascular disease and liver fibrosis clinically. Graphical abstract