Normal people urine routine examination of urine glucose content is negative, when urine glucose appears (+ + + +), suggesting that a larger amount of glucose in the urine, is a more serious situation. Under normal circumstances the glucose in the blood through the glomerular filtration to the renal tubules, can be reabsorbed by all the renal tubules, so the normal human urine routine examination does not contain glucose, but the ability of the renal tubules to reabsorb glucose has a certain limit, when more than this limit there will be a positive glucose in the urine, when glucose appears in the urine blood glucose concentration is the renal glucose threshold. When glucose (+ + +) in the urine, can be seen in the following two cases: 1, diabetes, diabetic patients with elevated blood glucose significantly, a large amount of glucose filtration to the renal tubules, more than the renal glucose threshold, glucose will appear in the urine, with the degree of elevation of glucose is different, urinary glucose can be manifested as (+) to (++++), so urinary glucose (+ + +), suggesting that blood glucose may have been significantly higher, need to consult a doctor promptly. 2, the renal tubule reabsorption capacity of certain limits, when exceeding this limit, there will be positive glucose in urine, glucose concentration is the renal glucose threshold. 2, decreased renal glucose threshold, some patients with normal blood glucose may also appear urine glucose (+ + +), such as patients with chronic kidney disease, pregnant women, etc., can lead to a decrease in renal glucose threshold, will also appear positive urine glucose.