Provided herein are pharmaceutical formulations containing exendins, exendin agonists, or exendin analog agonists that are administered at therapeutic plasma concentration levels over a sustained period of time to lower total cholesterol levels; to lower LDL-cholesterol levels; to lower triglyceride levels; to treat dyslipidemia; to treat and slow the progression of atherosclerosis; and to treat, prevent, and reduce the risk of heart attacks and strokes in patients. In the pharmaceutical formulations and methods of the invention, the exendin may be exendin-4, an exendin-4 agonist, or an exendin-4 analog agonist. The pharmaceutical formulations may be polymer-based pharmaceutical formulations that may be administered once weekly. An exemplary pharmaceutical formulation comprises 5% (w/w) of exenatide, about 2% (w/w) of sucrose, and about 93% (w/w) of a poly(lactide-co-glycolide) polymer, wherein the poly(lactide-co-glycolide) polymer is in the form of microspheres encapsulating the exenatide.