This test is most commonly used to screen for possible diabetes. Most dietary carbohydrates end up as glucose in the blood. Glucose is a major source of energy for most cells of the body. Some cells (for example, brain and red blood cells) are almost totally dependent on blood glucose as a source of energy. The brain, in fact, requires that glucose concentrations in the blood remain within a certain range in order to function normally. Concentrations less than about 30mg/dl can produce confusion or unconsciousness. High glucose concentrations (greater than 300 mg/dl) may cause similar symptoms if associated with dehydration, infection, or acidosis.
The major hormone regulating glucose concentration in the body is insulin (although other hormones such as glucagon, epinephrine, and cortisol also affect it). Glucose levels are measured most commonly to diagnose diabetes, or to monitor how well diabetes is being controlled. Diabetes is a very common disease -- affecting about 2% of the general population. Diabetes results from deficient insulin or decreased sensitivity to insulin. The results of a urine glucose test are also abnormal in cases of renal glycosuria. This is a kidney disease where glucose leaks into the urine even when blood glucose levels are normal.
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