A pulmonary drug delivery system is disclosed, including a breath-powered, dry powder inhaler, and a cartridge for delivering a dry powder formulation. The inhaler and cartridge can be provided with a drug delivery formulation comprising, for example, a diketopiperazine and an active ingredient, including, peptides and proteins such as insulin and glucagon-like peptide 1 for the treatment of endocrine disease, for example, diabetes and/or obesity.