Glycosuria occurs when what happens in diabetes?

• A. Blood glucose exceeds renal threshold and spills into urine
• B. The kidneys fail to filter properly
• C. There is excessive water intake
• D. The liver fails to produce glucose

Answer: (A)

Glycosuria in diabetes happens because blood glucose levels become so high that the kidneys’ ability to reabsorb glucose is overwhelmed. Glucose is filtered by the kidneys and normally reabsorbed in the proximal tubule by transporters. When plasma glucose rises above the renal threshold (about 180 mg/dL for many people), these transporters saturate and cannot reclaim all the glucose, so it spills into the urine. This glucosuria then draws water with it (osmotic diuresis), contributing to increased urination and thirst. In older adults, this can worsen dehydration and electrolyte balance. The other options don’t describe this mechanism: glycosuria isn’t due to the kidneys failing to filter properly, excessive water intake, or liver failure to produce glucose.