Question

Normally no glucose is present in the urine. But in patients suffering from "Diabetes Mellitus" urinary glucose levels are high. Which of the following explanations is most correct?:

	Glucose transporters in the proximal tubule do not work well in the kidney of diabetic patients.
	Glucose transporters in the proximal tubule are saturated and therefore not all of the filtered glucose is reabsorbed.
	Glucose is secreted in the collecting duct.
	Glucose is secreted in the collecting duct in the presence of ADH.
	None of the above are correct.

Answer 1

Answer

Option B) Glucose transporters in the proximal tubule are saturated and therefore not all of the filtered glucose is reabsorbed.

• Normally, all the glucose filtered in the Bowman's capsule is reabsorbed in proximal convoluted tubule.
• There are glucose transporters in the membrane of proximal tubule that facilitate reabsorption.
• In diabetic patients, the blood glucose levels are above normal.
• When excess glucose is filtered (above transport maximmum of glucose), the GLUT transporters become saturatred and cannot reabsorb more glucose.
• The excess glucose is excreted in the urine.