A diabetes test helps assess blood glucose levels and determine whether a person may have diabetes or prediabetes. Early detection is important because persistently high blood sugar can affect the eyes, kidneys, nerves, heart, and blood vessels.

Common diabetes tests include fasting blood glucose, postprandial blood glucose, random blood glucose, and the HbA1c test. Fasting blood glucose measures sugar levels after a period without food, while postprandial testing measures glucose after a meal. An HbA1c test estimates average blood glucose levels over approximately two to three months.

Doctors may recommend testing for people experiencing increased thirst, frequent urination, unexplained weight changes, or persistent fatigue. Testing may also be advised for people with risk factors such as a family history of diabetes, excess body weight, or a sedentary lifestyle.

The preparation required depends on the test.…