Glucose, Serum (Fasting)

This test is done to help your healthcare provider learn more about your health, check how well certain parts of your body are working, and look for signs of a medical condition that may need treatment or further evaluation.

Your doctor may order this test to diagnose or monitor conditions like diabetes, prediabetes, or to check for low blood sugar (hypoglycemia). It’s also used during pregnancy to screen for gestational diabetes.

Before your test, your provider will give you specific instructions to follow. You may be asked to avoid certain foods, drinks, or medications for a period of time. Tell your care team about any allergies, prescriptions, supplements, or health conditions you have, and ask questions if anything is unclear.

You’ll need to fast (no food or drink except water) for 8–12 hours before the test. Avoid smoking and strenuous activity on the day of the test.

During the test, a trained member of your care team will carry out the procedure step by step, using equipment designed to gather accurate information about your body. The process is generally safe, and most people find it quick and comfortable, though you may feel slight pressure or brief discomfort.

A healthcare provider will draw blood from a vein in your arm. The sample is sent to a lab where glucose levels are measured using an enzymatic method.

Your results show whether your values fall within the normal range for this test. Values within the expected range usually suggest no cause for concern, while results that are higher or lower than normal may point to a condition that needs follow-up. Your provider will explain what your numbers mean and discuss any next steps with you.

Results are compared to general reference ranges, but your doctor will interpret them in the context of your medical history and symptoms. High or low readings may trigger further testing.