Exosomes are the smallest extracellular vesicles which are released during pregnancy by the placenta, umbilical cord, amniotic fluid and various cell membranes in the extracellular space. The content of exosomes during pregnancy is strongly related to various conditions such as gestational diabetes mellitus (GDM). Although it is well-known that GDM is characterized by different levels of chronic low-grade inflammation, complement system dysregulation, vascular dysfunction and platelet activation, there is little data characterizing the serum exosomal protein cargo of GDM patients and their associations to these processes. The aim of this study was to analyze the serum exosomal proteome of GDM patients, with focus on the platelet activation and the complement proteins and their relationship to serum biochemical parameters and other protein markers of lipid metabolism and prothrombotic factors.