Ketones are chemicals that the body releases when it breaks down fat to use for energy. The body does this when it doesn’t have enough insulin to enable the glucose to get from your blood into your cells, your body’s normal source of energy. When ketones build up in the blood, they make it more acidic. They are a warning sign that your diabetes is out of control or that you’re getting sick. High levels of ketones can poison the body. This can lead to diabetic ketoacidosis which is a medical emergency and leads to coma and death if left untreated.