The renal glucose threshold is the lowest blood glucose concentration at which glucose begins to appear in the urine; when the blood glucose concentration exceeds the renal glucose threshold the absorption of glucose by the proximal tubule reaches its limit and glucose begins to appear in the urine. The renal glucose threshold is normal for people whose blood glucose reaches 8.88 to 10.08 mmol/L (160 to 180 mg/dL) and therefore urinary sugar may also occur in normal people after a meal.