The high blood sugar of uncontrolled diabetes can result in dangerous complications. Diabetes is the most common cause of blindness, kidney failure, and non-traumatic amputation of the toes, feet, or legs. Uncontrolled diabetes can also lead to heart disease, stroke, and the nerve damage and decreased blood flow that can lead to amputation. People with diabetes may have life-threatening reactions to extremely high blood sugar, as well as extremely low blood sugar caused by diabetes medications.
Keeping your glucose levels close to normal will greatly lower your chances of developing long-term complications. If you already have complications, keeping your glucose levels close to normal will help keep these problems from getting worse.