The endocrine system plays a critical role in regulating physiological processes through the secretion of hormones. The transport and transformation of hormones within the body are vital in maintaining homeostasis and facilitating proper cellular function. Disruptions in these processes can lead to various pathophysiological conditions. This section reviews the roles of species transport mechanisms and their coupling to biochemical reactions, emphasizing their contributions to endocrine pathologies, with a particular focus on diabetes mellitus.