Key words: plasma Cathepsin D, metabolic syndrome, type 2 diabetes, fatty liver disease, insulin resistance, myosteatosis

"The entanglement of plasma Cathepsin D and metabolic disturbances: relevant insights in the metabolic syndrome"

Metabolic syndrome has become an escalating public health threat, which is strongly linked to type 2 diabetes and fatty liver disease. For the treatment of type 2 diabetes, organ-specific interventions are beneficial to achieve higher intervention efficiency via determining organ-specific insulin resistance. This research demonstrated plasma Cathepsin D (a lysosomal enzyme) might be a useful marker to determine hepatic insulin sensitivity in pre(diabetic) individuals, thereby providing support for clinicians to apply the organ-specific therapy for diabetic patients. Furthermore, this study also indicated that plasma Cathespin D is increased in type 2 diabetic patients, suggesting plasma Cathepsin D is likely involved in the pathogenesis of type 2 diabetes and can be a potential target for treatment of type 2 diabetes. Considering no effective pharmaceutic therapy for fatty liver disease, this thesis proposes that plasma Cathepsin D might be a promising target for the prevention and treatment of fatty liver disease as insulin resistance might contribute to fatty liver disease progression via elevation of plasma Cathepsin D.