The A1C test is a common blood test used to diagnose type 1 and type 2 diabetes and to monitor how well you're managing your diabetes. The A1C test goes by many other names, including glycated hemoglobin, glycosylated hemoglobin, hemoglobin A1C and HbA1c.
The A1C test result reflects your average blood sugar level for the past two to three months. Specifically, the A1C test measures what percentage of your hemoglobin — a protein in red blood cells that carries oxygen — is coated with sugar (glycated). The higher your A1C level, the poorer your blood sugar control and the higher your risk of diabetes complications.
The A1C test measures your average blood sugar level for the past two to three months. The results of your A1C test can help your doctor:
Monitor your diabetes treatment plan. The results of your initial A1C test(s) also help establish your baseline A1C level. The A1C test is then repeated on a regular basis to monitor your diabetes treatment plan.
It measures your average blood sugar level for the past two to three months and can show how well your diabetes treatment plan is working to lower your blood sugar over time.
How often you need the A1C test depends on the type of diabetes you have, your treatment plan and how well you're managing your blood sugar. For example, the A1C test may be recommended:
You may need more frequent A1C tests if your doctor changes your diabetes treatment plan or you begin taking a new diabetes medication.
The A1C test is a simple blood test. You don't need to fast for the A1C test, so you can eat and drink normally before the test.
During the A1C test, a member of your health care team takes a sample of blood by inserting a needle into a vein in your arm or pricking the tip of your finger with a small, pointed lancet. If the blood is taken from a vein, the blood sample is sent to a lab for analysis. Blood from a finger prick is usually analyzed in your doctor's office for same-day results. You can return to your usual activities immediately.
A1C test results are reported as a percentage. A higher A1C percentage corresponds to higher average blood sugar levels. The higher your A1C level, the higher your risk of developing diabetes or complications of diabetes.
For someone who doesn't have diabetes, a normal A1C level is below 5.7 percent. If your A1C level is between 5.7 and 6.4 percent, you have prediabetes (also called impaired fasting glucose), which means you have a high risk of developing diabetes in the future.
An A1C level of 6.5 percent or higher on two separate occasions shows that you have diabetes. An A1C level above 8 percent means that your diabetes is not well-controlled and you have a higher risk of developing complications of diabetes.
For most adults who have diabetes, an A1C level of 7 percent or less is a common treatment target. Lower or higher targets may be appropriate for some individuals. If your A1C level is above your target, your doctor may recommend a change in your diabetes treatment plan.
Some people who have diabetes monitor their blood sugar levels at home with devices. Your devices likely report your blood sugar levels in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). A1C levels are reported as a percentage, but they correspond with estimated average blood sugar (glucose) levels. To help you tie your A1C levels back to your home monitoring, here's how A1C corresponds to the estimated average blood sugar level:
|A1C level||Estimated average blood sugar (glucose) level|
|6 percent||126 mg/dL (7 mmol/L)|
|7 percent||154 mg/dL (8.6 mmol/L)|
|8 percent||183 mg/dL (10.2 mmol/L)|
|9 percent||212 mg/dL (11.8 mmol/L)|
|10 percent||240 mg/dL (13.4 mmol/L)|
|11 percent||269 mg/dL (14.9 mmol/L)|
|12 percent||298 mg/dL (16.5 mmol/L)|
It's important to note that the effectiveness of A1C tests may be limited in certain cases. For example:
Also keep in mind that the normal range for A1C results may vary somewhat among labs. If you consult a new doctor or use a different lab, it's important to consider this possible variation when interpreting your A1C test results.