Final answer:
When the tubular fluid level of glucose exceeds the transport maximum for glucose reabsorption of 320 mg/min, the excess glucose is excreted in the urine, a condition known as glucosuria.
Step-by-step explanation:
If the tubular fluid level of glucose exceeds 320 mg/min, which is the transport maximum for glucose reabsorption, then the excess glucose will not be reabsorbed by the kidneys and will instead be excreted in the urine. The renal threshold for glucose is 180 mg/100 ml of blood. When the glucose concentration in the blood exceeds this value, the kidneys cannot reabsorb additional glucose, leading to its excretion. This condition, called glucosuria, often occurs in individuals with diabetes mellitus, where despite the presence of glucose transport proteins, or GLUTs, the amount of glucose filtered by the kidneys exceeds the capacity for reabsorption due to uncontrolled high blood glucose levels.