Healthy people who do not have diabetes have a normal level for hemoglobin A1c that is below 5.7 percent. The range for pre-diabetes is between 5.7 and 6.4 percent, while a level that is higher than 6.5 can be an indication of diabetes, states the National Institutes of Health's MedlinePlus.
The hemoglobin A1c test is used to detect the level of blood sugar level over a 3-month period. The test can also be useful for diagnosing diabetes or monitoring how well a patient is controlling the disease. Patients who have a hemoglobin A1c level that is 8 percent or over may have uncontrollable diabetes, notes Mayo Clinic.
Diabetes is a serious condition that can lead to many other health issues. When A1c levels are very high, it can also increase a person's risk factor for other health issues, including cardiovascular and renal disease.