The A1C test shows a patient's average blood glucose level over the last three months, expressed as a percentage, according to the National Institute of Diabetes and Digestive and Kidney Diseases. An estimated average glucose conversion chart expresses A1C test results in milligrams per deciliters.
The A1C test works by measuring the attachment of blood glucose to hemoglobin, the oxygen-carrying protein in red blood cells, explains the National Institute of Diabetes and Digestive and Kidney Diseases. Health care professionals can use the A1C test to diagnose type 2 diabetes and prediabetes.
GroupHealth provides an estimate average glucose, or eAG, conversion chart on its website. A higher eAG indicates that the patient is at a higher risk for health issues related to high blood sugar.