Grocery Coupons

Grocery Coupons

Members can print free savings coupons

Brain Health Center

Brain Health Center

Learn how to live smart and stay sharp

Amazon Kindle

Amazon Kindle

Members save on e-
readers and tablets

Caring for loved ones?

Caring for loved ones?

Find the resources you need


Diseases & Conditions A - Z
powered by healthline

Blood Sugar Test

What Is a Blood Sugar Test?

A blood sugar test is a simple procedure that measures the amount of glucose in the blood. It is performed by obtaining a small sample of blood and analyzing it. Blood can be obtained from a vein puncture or through a finger stick.

What Does a Blood Sugar Test Do?

Glucose is one of the body’s main sources of energy. Various types of foods, especially carbohydrates, grains, and fruits, are converted into glucose and can raise blood sugar levels in the body. A blood sugar test measures the amount of blood sugar or glucose in the body. It can be useful in diagnosing diabetes. It can also help diabetics manage their condition.

Who Benefits from a Blood Sugar Test?

Blood sugar tests are vital for anyone who is a diabetic. In addition, anyone who experiences symptoms of high or low blood sugar is a candidate for a blood sugar test. Monitoring levels is essential in order to determine how much insulin to take. People who are taking medications that can raise blood sugar levels, such as steroids, can also benefit from a blood sugar test.

Pregnant women and people who have a hard time controlling blood sugar levels should take routine blood sugar tests (American Diabetic Association).

What Are the Side Effects of a Blood Sugar Test?

Blood sugar tests do not usually cause many side effects. Blood sugar tests performed through a vein puncture can cause swelling and bruising at the puncture site. Blood sugar tests performed with a finger stick do not usually cause side effects other than possible soreness at the puncture site.

How Is a Blood Sugar Test Administered?

A blood sugar test is administered using a small needle and a blood glucose meter. Many different types of machines can be used for testing.

A blood sugar test can be performed in the hospital but it is also routinely done at home. If a blood sample is taken from the vein, the procedure will usually be done at the hospital or in a lab by a trained technician or phlebotomist. In many instances, a blood sugar test can be performed by obtaining a small amount of blood from a finger. The exact steps vary depending on the type of glucose meter a person is using. Many types of meters use glucose test strips. The steps for blood sugar testing usually include:

  1. Gather the necessary equipment and follow the glucose meter manufacturer’s instructors.
  2. Wipe the finger with antiseptic to prevent infection.
  3. Puncture the skin to draw a small amount of blood.
  4. Place a few drops of blood on the test strip for the meter to analyze.

What Are the Benefits of Blood Sugar Tests?

A blood sugar test can play a critical part in managing diabetes. The test identifies when glucose levels are too high or too low. This helps someone know when to take insulin. Monitoring blood sugar levels also provides information on how well a person’s diabetes is being controlled and how stable blood sugar levels are.

What Are the Risks of Blood Sugar Tests?

Very few risks are associated with a blood sugar test. Excess bleeding can occur, but it is unlikely. Any time the skin is punctured, infection is a risk, but it is also unlikely. Not having enough blood or getting an inaccurate reading are also risks of the procedure.

How Does a Patient Prepare for Blood Sugar Tests?

Some blood sugar tests require preparation. Fasting blood sugar tests require that a patient refrain from eating for 12 hours prior to the blood test. Non-fasting blood sugar tests do not require any special preparation.

What Are the Results of Blood Sugar Tests?

With a glucose meter, the results of a blood sugar test are immediate.

Normal values for a fasting blood sugar test are blood sugar levels below 100 milligrams per deciliter (mg/dL). Normal levels for a random blood sugar test done without fasting vary based on the food eaten by the patient. In general, a blood sugar level of less than 125 mg/dL is considered normal (University of Maryland Medical Center).

According to the American Diabetic Association, people who already have been diagnosed with diabetes will have targeted blood sugar levels. These are individualized and based on age, duration of diabetes, and other individual factors.

Content licensed from:

Written by: MaryAnn DePietro
Medically reviewed : George Krucik, MD, MBA

This feature is for informational purposes only and should not be used to replace the care and information received from your healthcare provider. Please consult a healthcare professional with any health concerns you may have.
Symptom Search
Enter your symptoms in our Symptom Checker to find out possible causes of your symptoms. Go.
Drug Interaction Checker
Enter any list of prescription drugs and see how they interact with each other and with other substances. Go.
Pill Identifier
Enter its color and shape information, and this tool helps you identify it. Go.
Drugs A-Z
Find information on drug interactions, side effects, and more. Go.
AARP Driver Safety


Discounts & Benefits


tax form

AARP Foundation Tax-Aide

Find a free Tax-Aide location
near you.

AARP In Your Corner

Visit Black Community, Español  and Asian Community pages.

AARP Drivers Safety logo

Driver Safety Program

Register at a location near you to keep your driving skills sharp. 

Create The Good 

Find opportunities to volunteer in your neighborhood. 

AARP Drive to End Hunger logo

Drive to End Hunger

NASCAR champ Jeff Gordon teams up with AARP's Foundation. 


Green Dot Prepaid Card

Prepaid MasterCard

AARP Foundation Prepaid MasterCard brought to you by Green Dot.

Most Popular


Nothing has been viewed