Lung–kidney system ↗Glomeruli filter circulating glucose
Filtered glucose load reflects plasma concentration and filtration rate; glucose enters tubular fluid with other small solutes.
KIDNEYS + METABOLISM / 09
Filter glucose.
Usually reclaim it.
Filtered glucose is normally recovered by proximal sodium-glucose cotransport. The kidney also contributes to insulin metabolism and the clearance of many medicines.
SGLT2 performs high-capacity reclamation
Early proximal tubular SGLT2 cotransports sodium and most filtered glucose into epithelial cells.
SGLT1 reclaims much of the remainder
Later proximal SGLT1 has lower capacity and higher affinity, providing additional recovery before urine leaves the nephron.
Glycosuria appears when reabsorption is exceeded
High filtered load, transporter inhibition, or tubular dysfunction can permit glucose to remain in urine.
SGLT2 inhibition changes the proximal route
Reduced glucose and sodium reabsorption increases urinary glucose, osmotic load, and distal solute delivery.
Downstream effects are distributed
Fluid, filtration, tubuloglomerular feedback, substrate handling, infection risk, and ketoacidosis context can all change.
Kidneys metabolize circulating insulin
Filtered and peritubular insulin can be taken up and degraded along the nephron, contributing to systemic clearance.
Kidney function changes medication exposure
Renally eliminated medicines require product-specific assessment using current function, body context, indication, and interacting drugs.