Which test is used to monitor long-term glucose levels in the blood?

The A1C test, also known as the glycosylated hemoglobin test, is specifically designed to measure the average blood glucose levels over the past two to three months. This is achieved by assessing the percentage of hemoglobin that has glucose attached to it. The presence of glucose attached to hemoglobin reflects the overall glucose control in the body over an extended period, making it an invaluable tool for managing diabetes and understanding long-term glucose control.

In contrast, the fasting blood glucose test measures blood sugar levels after a period of fasting, typically overnight, and provides information about the glucose levels at a specific point in time rather than over an extended duration. While the random blood sugar test can show how glucose levels fluctuate during the day, it does not provide insight into long-term trends. The oral glucose tolerance test is useful for evaluating how the body processes glucose but also focuses on a snapshot of how the body responds to glucose intake, rather than chronic levels. Therefore, the A1C test is the most appropriate choice for monitoring long-term glucose levels in the blood.