August 23, 2000
Diagnosis and Symptoms
Question from Florida, USA:
I read that a person can have elevated blood sugars, but not have any glucose appear in their urine. Approximately, what is the time frame for glucose to appear in the urine, after signs and symptoms of diabetes are apparent, and can a person have diabetes, but not yet spill glucose in their urine, but just have elevated blood sugars, as the only sign? Or slowly begin to exhibit signs, such as increased thirst and hunger, but not yet have sugar in their urine?
The question you pose is one of renal threshold, meaning at what point the kidney will spill extra sugar in the urine. It is stated in diabetes journals that most people will have a renal threshold of approximately 180 mg/dl (10 mmol/L)– when the blood sugar reaches 180 mg/dl (10 mmol/L) it will then begin to “spill” sugar into the urine. This number is not the same for everyone and can be higher or lower. Diabetes is diagnosed and managed by the measurement of blood sugar rather than urine sugar.