Hemoglobin A1C (HbA1C) or simply A1C is one of the commonly used tests to diagnose prediabetes, type 1 and type 2 diabetes, as well as the main test to help manage diabetes. This simple blood test measures a person’s average blood sugar levels over the past 2- 3 months.

When sugar enters the bloodstream, it attaches to hemoglobin—a protein in red blood cells that carries oxygen. Everyone has some sugar attached to the hemoglobin; however, people with higher blood sugar levels have more. The A1C measures the percentage of the hemoglobin that is coated with sugar.

The higher your A1C, the greater your risk for developing type 2 diabetes. A normal A1C level is at or below 5.6 %. A level of 5.7% to 6.4% indicates prediabetes and a level of 6.5% or more indicates diabetes. The goal for most individuals with diabetes is an A1C of less than 7%. Higher A1C levels are linked to diabetes complications (eye, kidney, heart, and nerve disease). Therefore, reaching and maintaining the individual A1C goal is important if you have diabetes. However, the personal goal will depend on many things such as age and other medical conditions.

A1C is a simple test done at the doctor’s office by using a sample of blood from a finger stick or from the arm; no need to do anything special to prepare. It doesn’t require fasting, and it reflects chronic exposure to glucose for people with and without diabetes.

How often you need to have A1C tested depends on the type of diabetes, the treatment plan and how well you are meeting treatment goals. A1C is tested once a year if you have prediabetes, every 6 months if A1C is below 6.9% and every 3 months if A1C is above 7%.

The American Diabetes Association (ADA) recommends that everyone 45 years of age and older have at least one A1C test. If results are normal, the A1C should be repeated every three years. If results are suggestive of prediabetes, the A1C should be checked at least annually. Those who were diagnosed with gestational diabetes (diabetes during pregnancy) that resolved after the baby was born, should be tested at least every three years for the rest of their life.

For those who are overweight or obese and have one or more risk factors for developing type 2 diabetes, they should have A1C tested as part of an annual medical exam. The risk factors include: a parent or sibling with diabetes, being physically inactive, high blood pressure, high triglyceride, low HDL cholesterol level, history of heart disease, high risk ethnicity (Native American, African American, Latino and Asian American).

There are several health conditions that can falsely increase or decrease A1C results such as sickle cell anemia, thalassemia, kidney failure, liver disease, enlarged spleen, pregnancy, blood transfusion and blood hemorrhage. Certain medications or dietary supplements may also affect the test and provide people with inaccurate results. They include opioids, certain drugs that are used to treat HIV, iron supplements and vitamin C supplements.

Talk to your healthcare provider to determine if you should have your A1c tested and what your personal goals should be.