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? (A) dipstick tests are more sensitive for reducing sugars other than glucose (B) the patient has defective tubular glucose transporters (C) the patient has diabetes insipidus (D) the patient has significantly reduced GFR (E) the patient is in a state of antidiuresis