The investigation of glomerular glucose transporters followed the identification of relatively higher levels of glucose transporters in the renal tubules (23,24). The first glomerular glucose transporter identified was GLUT1 (24,25), previously known as the red blood cell and brain glucose transporter (26,27). The term "GLUT" refers to facilitative glucose transporters, of which 12 are currently known (18,20). Subsequently, the GLUT3, GLUT4, GLUT5, and GLUT8 isoforms were discovered in glomeruli (24,28,29). GLUTs 3, 4, and 8 are high-affinity facilitative glucose transporters, whereas GLUT5 is predominantly a fructose transporter, with less glucose transport activity. In addition, there are reports of sodium-glucose cotransporter activity, possibly SGLT1, in glomerular mesangial cells (MCs) and podocytes (30,31). These latter reports remain to be confirmed and the transporters more thoroughly characterized. A description of the glomerular glucose transporters identified to date and their responses to diabetes, are provided below and in Table 1.
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