What A1C level is indicative of diabetes?

An A1C level above 6.5% is indicative of diabetes because it represents a chronic elevation in blood glucose levels over the past two to three months. The A1C test measures the percentage of hemoglobin proteins in the blood that have glucose attached to them. A level above 6.5% signifies that the average blood glucose level has been higher than normal, meeting the diagnostic criteria for diabetes established by the American Diabetes Association.

For context, an A1C level below 5.7% is considered normal, while levels between 5.7% and 6.4% indicate a state known as prediabetes, where individuals are at risk of developing type 2 diabetes. A level above 12% suggests very poorly controlled diabetes and typically reflects a need for immediate medical attention.