The A1C test is a blood test used to monitor your blood sugar control, giving you a snapshot of your average blood sugar control from the previous two to three months. It's an important number. Along with daily blood sugar tests that you do on your own, the A1C test helps your healthcare professional determine whether your diabetes management plan is working. If your A1C number is too high, then lifestyle changes and/or medicines may be needed. A good A1C number is 6.5 percent or less for most people. When A1C numbers rise above the target goal, the risk of having other serious health problems increases significantly.