SLC2A4 and metabolic syndrome: GLUT4 as the insulin-responding glucose transporter has been found expressed in neurons in hippocampus and involved in memory function (Birnbaum, 1989; McNay and Pearson-Leary, 2020; Fazakerley et al., 2022), and its defects are observed in IR and metabolic syndrome (McNay and Pearson-Leary, 2020; Yu et al., 2022).