Methods of treating metabolic diseases and disorders using a composition comprising a GLP-1/GIPR antigen binding protein fusion protein are provided. In various embodiments the metabolic disease or disorder is type 2 diabetes, obesity, dyslipidemia, elevated glucose levels, elevated insulin levels and diabetic nephropathy. In certain embodiments the composition comprises the C-terminus of a GLP-1 analog fused to the N-terminus of the light chain variable or heavy chain variable region of an antibody or functional fragment thereof that binds GIPR, optionally with a linker in between.