Microencapsulation has been explored as a promising method for controlled drug release. Polymeric microspheres, for example polylactic acid (PLA), polyglycolic acid (PGA) and poly(D,L-lactide-co-glycolide) (PLGA), can be used as effective drug delivery systems protecting the encapsulated active agent and controlling the release rate over periods of hours to months. By applying the correct methodology when preparing microspheres, challenges such as targeting the drug to a specific organ or tissue, and precisely controlling the rate of drug delivery to the target site can be addressed. The technique of double water-in-oilin-water (w/o/w) emulsion has been widely used for the encapsulation of hydrophilic drugs as this preparative method minimises the loss of drug activity via contact with the organic solvent. The basis of this methodology is to emulsify an aqueous solution of the active compound in an organic solution of the hydrophobic coating polymer. Then, this primary water-in-oil (w/o) emulsion is dispersed in a second aqueous phase, forming a double waterin-oil-in-water (w/o/w) emulsion. The solid microsphere is produced as the organic solvent evaporates. In this work, we prepared blank PLGA microspheres (containing no polypeptide) of grades 50:50 and 75:25 (lactide:glycolide ratio), using the double emulsion process. Using the same technique, we also loaded PLGA microspheres at low and high concentrations of exendin-4, a glucose-dependent insulinotropic polypeptide used to treat type 2 diabetes. The microspheres were subsequently freeze-dried. The objective of this work was to prepare, characterise, and understand the structural dynamics of these peptide loaded biodegradable polymeric microspheres.