It may be used to diagnose diabetes , monitor diabetic control, or as a screening test. Most dietary carbohydrate eventually ends up as glucose in the blood.
Excess glucose is converted to glycogen for storage by the liver and skeletal muscles after meals.
Glycogen is gradually broken down to glucose and released into the blood by the liver between meals. Excess glucose is converted to triglyceride for energy storage. Glucose is a major source of energy for most cells of the body. The brain, in fact, requires that glucose concentrations in the blood remain within a certain range in order to function normally. Glucose levels are measured most commonly to diagnose diabetes or to monitor adequacy of diabetic control.