When a person does not take their insulin, their blood sugar can rise to dangerous levels, according to Drugs.com. If a person's blood sugar stays high or is high frequently, it can damage their health significantly.
Insulin is used to keep blood sugar levels within a normal range, as stated by the New York State Department of Health. For most people, the normal, healthy range falls between 90 and 130 mg/dl though it will rise after a meal. If the body fails to have enough insulin, it can result in blindness and kidney problems. A doctor can prescribe various types of insulin.