An A1C test, also known as hemoglobin A1C, HbA1c, or glycated hemoglobin test, is a blood test that measures your average blood glucose (sugar) level over the past 2 to 3 months. It works by measuring the percentage of hemoglobin (a protein in red blood cells) that is coated with glucose. Since red blood cells live about three months, the test gives an average indication of blood sugar levels during that period. This test is important for diagnosing and monitoring diabetes and prediabetes. Higher A1C percentages indicate higher average blood sugar levels, which can increase the risk of diabetes complications such as heart disease, kidney disease, and nerve damage. The A1C test does not require fasting and provides a bigger picture of glucose control compared to single-point blood sugar tests. Normal A1C levels are below 5.7%. Levels between 5.7% and 6.4% suggest prediabetes, and levels of 6.5% or higher indicate diabetes. For people with diabetes, the test helps evaluate how well their blood sugar is being managed. The A1C test is usually done every 6 months or more frequently depending on individual treatment goals and conditions. It is a key tool for managing and diagnosing diabetes and guiding treatment decisions. In summary, the A1C test provides a snapshot of your average blood sugar control over a few months, useful for diagnosing diabetes, prediabetes, and managing diabetes treatment effectively.