Your body converts the carbohydrates, which you eat into glucose.

Glucose testing is primarily done for people with type 1 diabetes, type 2 diabetes, and gestational diabetes. Diabetes is a condition that causes your blood glucose levels to rise.

The amount of sugar in your blood is usually controlled by a hormone called insulin. However, if you have diabetes, your body either doesn’t make enough insulin or the insulin produced doesn’t work properly. This causes sugar to build up in your blood. Increased levels of blood sugar can lead to severe organ damage if left untreated.

In some cases, blood glucose testing may also be used to test for hypoglycemia. This condition occurs when the levels of glucose in your blood are too low.

How to prepare for a fasting blood glucose test

For a fasting blood glucose test, you can’t eat or drink anything but water for eight hours before your test. You may want to schedule a fasting glucose test first thing in the morning so you don’t have to fast during the day. Fasting tests are common because they provide more accurate results and are easier to interpret.


Before your test, tell your doctor about the medications you’re taking, including prescriptions, over-the-counter drugs, and herbal supplements. Certain medications can affect blood glucose levels. Your doctor may ask you to stop taking a particular medication or to change the dosage before your test temporarily.

What to expect during a fasting blood glucose test

Your doctor will require a blood draw from a vein.

Before drawing blood, the healthcare provider performing the draw cleans the area with an antiseptic to kill any germs. They next tie an elastic band around your upper arm, causing your veins to swell with blood. Once a vein is found, they insert a sterile needle into it. Your blood is then drawn into a tube attached to the needle.

You may feel a slight pain when the needle goes in, but you can reduce the pain by relaxing your arm.

When they’re finished drawing blood, the healthcare provider removes the needle and places a bandage over the puncture site. Pressure will then be applied to the puncture site for a few minutes to prevent bruising.

The sample of blood is then sent to Lab24 for testing. Your doctor will follow up with you to discuss the results.