CP-91149 is primarily used in biochemical and pharmacological research as a potent and selective inhibitor of glycogen phosphorylase, an enzyme involved in glycogen breakdown. Its main application lies in studying glucose metabolism, particularly in the context of type 2 diabetes, where modulating glycogenolysis can help control elevated blood glucose levels. Researchers use CP-91149 to probe the role of liver glycogen phosphorylase in metabolic pathways and to evaluate the therapeutic potential of enzyme inhibition in metabolic disorders. Due to its specificity, it serves as a valuable tool compound in developing insulin-sensitizing agents and understanding hepatic glucose production. It is not used clinically but remains important in preclinical research for metabolic disease drug discovery.