If your blood glucose level for this screening is higher than 200 mg/dL, most practitioners will consider you diabetic and you won't be required to take the glucose tolerance test. But any score between 140 and 200 means that you'll have to take the three-hour glucose tolerance test for a definite diagnosis.
The purpose of homeostasis is to maintain a normal balance within the body regarding its temperature, salt concentration, water concentration, and food intake. The human body functions normally with a narrow range of variation for each of these factors.
The work that your body does to maintain internal balance and equilibrium is called homeostasis. You have tons of sensors that monitor your body. If a signal is received because some value has deviated from normality, that value will be restored to keep you safe.