A glucose urine test can be used to check levels of glucose in urine. Any result other than zero is bad, as urine should not contain glucose. If there is glucose in the urine, that is a sign that the level of blood sugar in the blood is high.
Glucosuria or glycosuria is term that is used to describe presence of glucose in the urine. As we mentioned, there should be no glucose in the urine at all, as the nephrons in the kidneys reabsorb all glucose from the primary urine back into the bloodstream. If high glucose levels in the blood remain untreated (as in diabetes mellitus), then glucose can be found in urine. Other conditions that cause the presence of glucose in the urine are renal glycosuria and even and excessive consumption of carbohydrates (sweets and soft drinks).
Function of glucose
In the body, carbohydrates are converted (broken down) into glucose, which then serves as provider of energy for various metabolic processes in the body. Level of glucose that is present in the blood is regulated by hormone insulin. If glucose level in the blood is high, pancreas secretes insulin and lowers the level of glucose in the blood by initiating its conversion to form more suited for prolonged storage (like conversion to fat).
Levels of blood sugar normally oscillate throughout the day, typically being low in the early morning and rising after every meal. Anything between 70 and 150 mg per liter of blood is fine. There is no normal glucose level in urine, unless you want to regard a "zero" as a level. There should be no glucose in urine, ever. If there is too much of it in the blood, then the kidneys can not reabsorb it all and some glucose will end up in urine. How much is too much is determined by the value known as renal threshold of glucose or RTG. If your RTG is low then you may have some glucose in the urine even if your blood sugar is within normal levels.
How to determine if there is glucose in the urine?
The "spot test" is used to determine if there is glucose present in the urine. It is based on reaction of chemicals found in the pad on the dipstick used for the test. The pad is colored, and the chemicals in it, when they react with glucose, will make it to change color. This means that, if there is glucose in the urine, the color changes while, if there is no glucose in the urine, the color of the pad remains unchanged. The shade and color of the pad show the concentration of glucose in urine, when compared to a reference color chart. There are other tests, mostly based on the same principle.