MEDICAL ANIMATION TRANSCRIPT: An A1C test is a blood test that can be used to estimate the average amount of glucose, or sugar, in your blood over the past three months. Other names for this test are HbA1c, glycated hemoglobin, and glycosylated hemoglobin. This test is often used to screen for or manage diabetes and pre-diabetes, conditions that can happen when your blood sugar is too high. In order to understand how the test works, it's important to know about red blood cells and how your blood sugar affects them. Most of the cells in your blood are called red blood cells. They are made in your bone marrow, which is the tissue in the center of your bones. From there, they travel to your lungs where they pick up oxygen from the air you breathe in. This happens in tiny air sacks in your lungs called alveoli. Here, oxygen attaches to proteins inside your red blood cells called hemoglobin. Your red blood cells then deliver the oxygen to tissues throughout your body. After about three mont...