One of your diabetic patients has a blood glucose level of 200 mg/dL. Surprisingly, a dipstick test is negative for urinary glucose. How could this finding be explained?

Question

Quizplus · Accepted Answer

The patient has significantly reduced glomerular filtration rate (GFR). Glucose excretion by the kidneys depends on the glomerular filtration and tubular reabsorption rates. Glucose first appears in the urine when the capacity of the glucose transporters in the proximal tubuli cells is exceeded. This usually occurs at plasma glucose levels higher than 180 mg/dL. Patients with longstanding diabetes mellitus often have decreased renal function and reduced GFR. Under these circumstances the threshold (ie, plasma level) for excretion of glucose is higher than in a healthy person.

One of Your Diabetic Patients Has a Blood Glucose Level