Auntie Zhang found sugar (+) in her urine during a unit checkup and thought she was suffering from diabetes, but after repeatedly checking her fasting and postprandial glucose at the hospital’s endocrinology department, the doctor denied her diagnosis of diabetes. It turns out that a positive urine sugar level depends on two factors: the blood sugar level and the renal sugar threshold level. When the blood glucose level is too high, exceeding 160mg/dL, the sugar leaks out of the urine, and the blood glucose level at this time is the normal renal sugar threshold; on the other hand, if the renal sugar threshold is too low, even if the blood glucose is normal, the urine will be positive for sugar, called renal diabetes. The urine test strip method used to measure glucose is based on the principle of glucose oxidase method, therefore, if the urine is mixed with disinfectants (such as bleach, hypochlorite), after taking a large amount of vitamin C, pioneer amycin, remifung, aspirin and other drugs can make a false positive reaction of urine sugar. In diabetes, positive urine sugar, but positive urine sugar is not necessarily diabetes, there are many reasons can cause a positive urine sugar test: 1, elevated glucose diabetes: In addition to diabetes, some other endocrine diseases that promote excessive secretion of blood sugar hormones such as: hyperthyroidism, anterior pituitary hyperfunction, pheochromocytoma, Cushing’s syndrome, etc. can appear diabetes. 2, renal diabetes: because the normal blood glucose sugar from the glomerular filtration, almost all reabsorption in the proximal tubule of the kidney, when the proximal tubule of glucose reabsorption function is reduced, the renal sugar threshold is reduced, diabetes. Can be seen in familial diabetes, chronic nephritis or nephropathy, acute and chronic interstitial nephritis with renal tubular dysfunction, a few pregnant women also have a temporary reduction in renal sugar threshold and diabetes. 3, temporary diabetes: more than the renal sugar threshold of physiological diabetes, such as ingestion of large amounts of carbohydrates or injection of a large number of glucose sugar, can be a transient increase in blood sugar, urine sugar positive. Stress glycosuria can also appear temporary elevation of blood glucose and positive urine sugar. 4, non-glucose urine: kidney tubules absorb lactose, galactose, fructose, mannose and some pentose sugar ability than glucose sugar, if the intake of this type of sugar too much (such as after eating a lot of fruit), or abnormal metabolism in the body so that its concentration in the blood is too high, will also appear diabetes. In lactating women, lactosuria can also occur due to excessive production of lactose by the mammary glands. Tubulointerstitial nephritis is the most common kidney disease causing glycosuria, which is a large group of kidney diseases caused by a variety of different causes. It is a large group of kidney diseases caused by different reasons. The lesions mainly invade the renal tubules and interstitial stroma; the clinical manifestations are highlighted by tubular dysfunction. According to the course of the disease, tubulointerstitial nephritis can be divided into two categories: acute and chronic; according to the etiology, there are infectious, drug-induced, immune-mediated and genetic metabolic disorders causing interstitial nephritis. Clinically, drug-induced cases are the most common, followed by complex chronic pyelonephritis with urinary tract obstruction.