The interplay of metabolic and signaling processes is prerequisite for the functionality of cells. Any disturbances may have severe consequences, resulting in the development of diseases. However, the complex coordination of metabolism and signaling events makes it difficult to decipher the link between molecular irregularities and pathogenesis. An excellent way to provide more clarity is to see into the living cell and watch cellular processes in real-time, with the add-on of being able to manipulate certain processes. Live cell imaging enables us to do exactly that, with steadily improving spatial and temporal resolution. Modern genetically encoded fluorescent probes in combination with state-of-the-art high-resolution imaging devices have proven themselves as a valuable approach for monitoring, manipulating and ultimately understanding the interaction of cell metabolism and signaling. These probes also represent powerful tools for detecting biomarkers of disease, identifying new drug targets and elucidating drug actions at the cellular to the molecular level.