Provided herein are methods for treating certain conditions, including diabetes, obesity, and other metabolic diseases, disorders or conditions by administrating a composition comprising a biguanide or related heterocyclic compound, e.g., metformin. Also provided herein are biguanide or related heterocyclic compound compositions, and methods for the preparation thereof for use in the methods of the present invention. Also provided herein are compositions comprising metformin and salts thereof and methods of use.