What test is commonly used to diagnose diabetes?

The hemoglobin A1c test is widely used to diagnose diabetes because it measures the average blood glucose levels over the past two to three months. This provides a more comprehensive picture of a person's blood sugar control compared to a single measurement taken at a specific point in time. The A1c test is particularly valuable because it is not influenced by short-term fluctuations in blood glucose levels, making it a reliable indicator of long-term glucose management.

In comparison, while the fasting blood glucose test, oral glucose tolerance test, and random blood glucose test are also used in diagnosing diabetes, they offer insights primarily into current glucose levels rather than reflecting the overall glycemic control over an extended period. The hemoglobin A1c test, due to its ability to encapsulate long-term control, often plays a central role in both the diagnosis and management of diabetes, making it a key tool in endocrinology.