The present invention features a compound having the formula A-X-B, where A is peptide vector capable of enhancing transport of the compound across the blood-brain barrier or into particular cell types, X is a linker, and B is a GLP-1 agonist (e.g., exendin-4 or an exendin-4 analog). The compounds of the invention can be used to treat any disease where increased GLP-1 activity is desired, for example, metabolic diseases, such as obesity and diabetes.
