Insulin receptor (IR) is a tyrosine kinase involved in vital cellular signaling processes related to glucose metabolism and cell growth. Detailed understanding of molecular mechanisms of IR signaling is important for improved treatments of diabetes and related disorders. Although many aspects of IR signaling have over the past years been elucidated, much of the available information comes from studies made in vitro, using protein preparations. However, observations performed directly in living cells, tissues and organisms are needed for proper understanding of IR signaling. To address this need, we decided to apply the powerful yet underutilized technique of polarization microscopy, which promised to offer a unique opportunity to study interactions of IR with its agonists and antagonists in living cells. Here we present our observations of GP2(1)-eGFP-CD59, a biosensor for polarization-resolved fluorescence microscopy, which allowed us to visualize, in living cells, changes in IR conformation induced by interactions with IR agonists and antagonists, but also, somewhat surprisingly, with kinase inhibitors. Our results open doors to sensitive imaging of various aspects of IR function in living cells, tissues, and ultimately whole organisms, under conditions close to natural.