The present invention relates to a use of cellular repressor of E1A-stimulated genes (CREG) protein, and in particular to a use of a CREG protein or an active fragment thereof in manufacture of a medicament for the prevention and/or treatment of a fatty liver disease and type 2 diabetes. The present invention also relates to a use of a recombinant vector or recombinant cell expressing a CREG protein or an active fragment thereof in manufacture of a medicament for the prevention and/or treatment of a fatty liver disease and type 2 diabetes. The invention also relates to a corresponding kit, such as a kit used for the predication and/or evaluation of therapeutic effect and prognosis of a fatty liver disease and type 2 diabetes.
