Hyperglycemia can be a serious problem if you don't treat it, so it's important to treat as soon as you detect it. If you fail to treat hyperglycemia, a condition called ketoacidosis (diabetic coma) could occur. Ketoacidosis develops when your body doesn't have enough insulin. Without insulin, your body can't use glucose for fuel, so your body breaks down fats to use for energy.
When your body breaks down fats, waste products called ketones are produced. Your body cannot tolerate large amounts of ketones and will try to get rid of them through the urine. Unfortunately, the body cannot release all the ketones and they build up in your blood, which can lead to ketoacidosis.
- See more at: http://www.diabetes.org/living-with-diabetes/treatment-and-care/blood-glucose-control/hyperglycemia.html?referrer=https://www.google.co.th/#sthash.P3C8jmNW.dpuf