Exenatide for use in a method of treating type 2 diabetes mellitus in a subject, wherein the subject is a human being, the treatment comprising: providing continuous administration of exenatide from an osmotic delivery device, having the exenatide the amino acid sequence of exendin-4 and comprising the osmotic administration device: an impermeable reservoir comprising inner and outer surfaces and first and second open ends； a semi-permeable membrane in sealing relationship with the first open end of the reservoir； an osmotic motor inside the reservoir and adjacent to the semi-permeable membrane； a piston adjacent to the osmotic engine, where the piston forms a movable joint with the inner surface of the reservoir, the piston divides the reservoir into a first chamber and a second chamber, the first chamber comprising the osmotic motor； a suspension formulation, the second chamber comprising the suspension formulation and the suspension formulation being able to flow, the suspension formulation comprising a particle formulation comprising exenatide and a vehicle formulation, wherein the vehicle formulation comprises a solvent and a polymer, wherein the solvent is selected from the group consisting of benzyl benzoate, lauryl lactate and lauric alcohol and the polymer is polyvinylpyrrolidone； and a diffusion moderator inserted into the second open end of the reservoir, the diffusion moderator adjacent to the suspension formulation； wherein (i) the substantial steady-state administration of exenatide at a therapeutic concentration is achieved within a period of time selected from the group consisting of 5 days or less, 4 days or less, 3 days or less, 2 days or less, and 1 day or less after implantation of the osmotic administration device in the human being, and (ii) the substantial steady-state administration of the exenatide from the osmotic administration device is continuous for a period of administration of at least 3 months at a dose of mcg / day of exenatide sele
