Glycerol 3-phosphate dehydrogenase (GPD1 and GPD2) are key enzymes in the glycerol 3-phosphate shuttle (GPS), which connects glucose and lipid metabolism and functions as an NADH shuttle for mitochondrial bioenergetics. GPD1 is cytosolic and NADH-dependent, converting dihydroxyacetone phosphate (DHAP) to glycerol 3-phosphate (G3P), while GPD2 is mitochondrial and FAD-dependent, converting G3P back to DHAP and transferring electrons to coenzyme Q (CoQ). Abnormal expression of GPD1 and GPD2 has been linked to various metabolic diseases and cancers. Recent studies have explored their roles in cancer and other diseases, revealing both tumor-suppressive and tumor-promoting functions. GPD1 generally acts as a tumor suppressor, with low expression correlating with poor survival in cancers like breast and kidney cancer. Conversely, GPD2 is often upregulated in cancers, contributing to tumor progression through mechanisms involving lipid metabolism, ROS production, and cell proliferation. GPD2's role in cancer is complex, with some studies suggesting it may also have tumor-suppressive effects under certain conditions. The GPS is a critical hub in glucose and lipid metabolism, and its dysfunction can lead to metabolic disorders. Despite extensive research, the exact mechanisms and therapeutic potential of targeting GPD1 and GPD2 in diseases remain areas of active investigation.Glycerol 3-phosphate dehydrogenase (GPD1 and GPD2) are key enzymes in the glycerol 3-phosphate shuttle (GPS), which connects glucose and lipid metabolism and functions as an NADH shuttle for mitochondrial bioenergetics. GPD1 is cytosolic and NADH-dependent, converting dihydroxyacetone phosphate (DHAP) to glycerol 3-phosphate (G3P), while GPD2 is mitochondrial and FAD-dependent, converting G3P back to DHAP and transferring electrons to coenzyme Q (CoQ). Abnormal expression of GPD1 and GPD2 has been linked to various metabolic diseases and cancers. Recent studies have explored their roles in cancer and other diseases, revealing both tumor-suppressive and tumor-promoting functions. GPD1 generally acts as a tumor suppressor, with low expression correlating with poor survival in cancers like breast and kidney cancer. Conversely, GPD2 is often upregulated in cancers, contributing to tumor progression through mechanisms involving lipid metabolism, ROS production, and cell proliferation. GPD2's role in cancer is complex, with some studies suggesting it may also have tumor-suppressive effects under certain conditions. The GPS is a critical hub in glucose and lipid metabolism, and its dysfunction can lead to metabolic disorders. Despite extensive research, the exact mechanisms and therapeutic potential of targeting GPD1 and GPD2 in diseases remain areas of active investigation.