Information regarding the renal glucose transport capacity in diabetes mellitus is limited. These data are needed because two weeks following injection of streptozotocin (STZ), mRNA and protein levels of the glucose transporter, GLUT2, are upregulated in the proximal tubule of the rat. Therefore, we measured renal glucose transport and GLUT2 protein levels in female control rats, and in rats one (STZ-1), two (STZ-2), and three weeks (STZ-3) after STZ injection (65 mg kg(-1), i.p.). Progressive amounts of glucose were infused into anesthetized rats via the femoral vein and renal clearances collected. The amount of glucose reabsorbed, factored by the glomerular filtration rate (GFR) was significantly greater in STZ-3 rats compared with all other groups. In addition, the amount of glucose reabsorbed factored by the amount of glucose filtered was decreased in STZ-1 and STZ-2 compared with controls but was increased in STZ-3. By contrast, renal GLUT2 levels were elevated in all the STZ-treated rats. These data suggest that other factors, functioning either in conjunction with or independent of GLUT2, are required to support an elevated renal glucose transport capacity.