Stephan Speier studied from 1995 to 2000 human biology at the Philipps-University in Marburg, Germany, with major in Physiology. Subsequently, he conducted his PhD-thesis project at the Max Planck Institute of Biophysical Chemistry in Göttingen, Germany, in which he developed the pancreas tissue slice platform to study islets of Langerhans in the in situ environment of intact organ tissue.

From 2005 to 2009 Stephan Speier worked as a postdoctoral fellow at the Karolinska Institutet in Stockholm, Sweden. Further pursuing his interest in the complex physiology of islets of Langerhans he and his colleagues established the anterior chamber of the eye model, and an exciting technical approach to assess islet cell biology longitudinally in vivo by noninvasive imaging at cellular resolution. In 2009 Stephan Speier was granted the prestigious Emmy Noether Fellowship by the German Research Foundation to establish his own research group at the Center for Regenerative Therapies Dresden, Germany. In 2016 he became Professor for the Physiology of Pancreatic Islet Cells at the Medical Faculty of the TU Dresden, Germany and in 2022 he was appointed Professor of Physiology and Director of the Institute of Physiology at the Medical Faculty of the TU Dresden, Germany, where he also heads the Islet Physiology research group of the Paul Langerhans Institute Dresden of the Helmholtz Zentrum Munich at the Technical University Dresden.

In his research, Stephan Speier studies the cells of the islet of Langerhans and their role in diabetes pathogenesis and therapy. A central aspect of his work is the translation of his findings to the human setting. To that aim he has successfully adapted the anterior chamber of the eye and tissue slice methodologies for the study of human pancreas. These approaches now enable the investigation of human islet cell physiology under close to physiological conditions in situ and in vivo.