Wikipedia in its article on 'Glycosuria' says that the renal threshold for glucose (RTG) reabsorption in the kidney is around 160-180 mg/dL. Beyond which the glucose starts to excrete in the urine. But in diabetic people blood glucose exceeds in range of 300-400 mg/dL is prevalent. How this is possible? What prevents the the excretion of excess glucose into urine?
Does it mean more glucose is reabsorbed in the nephrons above its threshold limit? Also, as the glucose is co-transported with sodium, does it mean that glucose reabsorption is tightly coupled with sodium reabsorption? Does sodium play any role in crossing the glucose threshold limit?
Or is it possible that the excess glucose (beyond RTG) is actually excreted out of blood in the kidney but the hyperglycemia is caused by the fresh gluconeogenesis of the body?
Or is it possible that both these mechanisms (RTG is exceeded as well as fresh gluconeogenesis) cause in furthering the hyperglycemia?
Is it possible to measure this state?
Thanks in advance.