What is finger stick testing?

Jules Walters • Published: Nov 27, 2023

Finger stick testing is a common way of getting a small blood sample from your finger. It involves pricking the fingertip with a tiny lancet to draw a drop of blood and putting the blood on a test strip to be inserted into a glucose monitor for analysis.

Why is finger stick testing done?

Finger stick testing is mainly done by people with diabetes to monitor their blood sugar levels regularly. It helps them manage their condition, and make informed decisions about medication and insulin doses. Testing also helps to understand how diet, physical activity, and other factors impact one’s blood sugar levels.

More recently, finger stick testing has expanded to healthy consumers interested in monitoring key biometrics. People who are non-diabetic can also benefit from checking their blood sugar levels for several reasons:

Early detection of diabetes – Routine blood sugar monitoring can help detect undiagnosed diabetes early on, especially among people with a family history of diabetes. It allows for early intervention and lifestyle changes, such as exercising more or reducing sugary foods, that can prevent or delay the onset of diabetes.

Identification of pre-diabetes –Pre-diabetes is a condition where blood sugar levels are higher than normal, but not high enough to qualify as diabetes. Regular blood sugar testing can help identify pre-diabetes, allowing people to make lifestyle modifications to prevent progression to diabetes.

Monitoring general health –Blood sugar levels can be an indicator of overall health. For non-diabetics, routine blood sugar checks can give insights into how diet, exercise and stress affect their blood sugar levels.

It’s important to note that finger stick testing alone can’t diagnose diabetes. If someone suspects they have diabetes, it’s best to talk to a qualified healthcare professional for additional testing and diagnosis.

How to perform a finger stick blood test

Finger stick testing is a simple and easy way to check your blood sugar levels. You can do it on yourself quite easily at home with a test kit available over the counter from most big pharmacies. You don’t need a prescription.

Firstly, lay out all the test kit parts. A blood glucose monitor (AKA a ‘glucometer’), test strips that work with the particular monitor, lancets, alcohol swabs, and a sealable sharps container. You can improvise for the container with a puncture-proof plastic tub, so long as it has a secure lid, and you clearly label it as a sharps container.

These are then the key steps for each test:

General preparation

Start by washing your hands with soap and water. This ensures the test isn’t contaminated by food or dirt that could affect the accuracy of the results. Dry your hands with a clean towel.

Have the portable blood glucose monitor and a fresh lancet ready on the table. A lancet is a small, needle-like device encased in plastic that you’ll use to prick your fingertip and obtain a drop of blood. The blood glucose meter will measure the glucose level in the blood drop and give you a digital read out.

Load the lancet

Lancets vary slightly in style and operation from one model to another, so follow the instructions on the lancet pack. Typically, though, the lancet needs to be inserted into a small, spring-loaded device. You’ll need to remove the safety cap from the lancet, then load it into the device.

You may also have an option to set the desired depth for the finger stick to penetrate your finger. If so, the depth setting will depend on your your comfort level with being pricked. It doesn’t need to be very deep to get a suitable drop of blood.

Prepare your finger

Choose a finger to prick. It’s common to use the sides of the fingertip, as they’re less sensitive. (You can also change fingers if you need to do it more than once.) Clean the chosen finger with the alcohol swab to disinfect and wait a few seconds for your finger to dry.

Prick your finger

Place the loaded lancet against the side or face of the fingertip. Press the trigger on the lancet device to prick the skin quickly and cleanly. A small drop of blood will form where the skin is punctured.

Collect blood sample

Gently squeeze or massage the finger to encourage a large enough blood drop to form. You may have to practice a few times to get a good drop of blood.

Put on the drop of blood on a test strip, either by touching the strip to the blood or placing the blood drop onto the strip in the meter. The exact method will depend on the type of glucose meter you use.

Obtain reading

Insert the test strip with the blood sample into the glucose meter. After a few seconds, the meter will display your blood sugar level. 

The difference between finger stick and venous blood tests

Finger stick blood tests and venous blood draws, meaning from your vein, are both common ways to get blood for medical testing. Here’s how they differ:

Location: Finger stick blood tests are performed by pricking your fingertip with a lancet to collect a small amount of blood. Venous blood draws involve inserting a needle directly into a vein, typically in the crook of the arm, to draw blood in greater volume.

Sample volume: Finger stick tests usually yield a small drop of blood, typically around 0.5 to 1.0 microliters, while venous blood draws collect several milliliters of blood, depending on what needs to be tested.

Presence of a healthcare professional: Finger stick tests can be done yourself or with the help of someone at home, as they’re simple and quick once you get the hang of it. Venous blood draws require a healthcare professional, who has been trained do to it and usually means leaving home to go to a testing lab. There are phlebotomists, who will come to your home, but that is more expensive.

Test compatibility: While many tests can be performed using both finger stick blood and venous blood, some blood draws will need more blood. That’s particularly so where multiple health markers are being checked at the same time.

Comfort and pain levels: Finger stick blood tests typically cause less discomfort or pain compared to venous blood draws, as the needle used is smaller, and the sampling process is faster and less invasive.

Frequently Asked Questions (FAQs)

Here are a few more questions that are often asked about finger stick testing.

Can you self-diagnose diabetes or pre-diabetes from a finger stick blood test?

No. The diagnosis of diabetes or pre-diabetes needs a medical professional to evaluate your symptoms, do additional tests, and consider factors such as medical history, family history, and other risk factors.

If you suspect you have diabetes or pre-diabetes, it is important to consult with a healthcare provider who can provide an accurate diagnosis and appropriate treatment options.

Where’s the best place on your hands to do finger sticks?

The common advice for collecting blood samples is to prick the sides of your fingers, as they’re less sensitive than the fleshy tips or pads. For most people, though, any pain felt from the needle prick is fleeting and minimal. And – in my experience – the difference in sensation between the tip and the side of the finger is only slight.

What exactly are lancets? Are they dangerous?

A lancet is a sharp medical instrument used to puncture the skin, typically for blood sampling or glucose monitoring. While they may sound dangerous, lancets are designed to be safe and to minimize discomfort.

For finger stick testing at home, you can use a special type of miniature lancet called a lancet pen or lancing device. They usually come with adjustable depth settings. These control the depth of the skin penetration, which you can adjust to suit your comfort level.

On a safety note: lancets for finger stick testing are for single use. So: never reuse lancets, and do dispose of each one carefully after use to minimize the risk of infection.*

How painful is finger stick testing?

As for the level of discomfort, the pain varies depending on your sensitivity and the technique used. However, with modern lancets and technical advances, the level of discomfort is generally minimal.

The sensation is often described as a brief pricking or stinging feeling. If, like me, you’ve had a few Covid shots in recent years, you may feel the lancet prick as being a bit like the vaccination needle going into your arm. You just don’t get that bruised feeling that often follows a vaccination.

What can you do to encourage blood flow after a finger prick?

Sometimes, it’s hard to even get one decent drop of blood from a finger prick, particularly if your hands are cold. So, as part of your preparation for the test, be sure to wash your hands in warm water immediately beforehand. Then shake off the excess and wipe them dry.

Can’t produce a big enough blood drop after the finger prick? Try hanging your hand below your waist for a few seconds. Then, squeeze your test finger, starting from the base, and move up towards the tip.

What’s the best way to dispose of finger stick testing supplies?

Place the used lancets and test strips into a puncture-resistant sharps container.*

Ideally, the container should be specifically designed for collecting and storing used medical sharps. However, if you can’t easily obtain one, you can always repurpose a robust plastic tub with a securable lid. That’s a hundred times better than simply throwing everything unsealed in the trash.

Ensure the sharps container is sealed securely each time you use it, to prevent accidental exposure or injury. When full, place the sealed sharps container in a sturdy plastic bag or container to provide an extra layer of protection.

If you don’t have access to a safe disposal service by mail, dispose of the bag and container in accordance with your local waste management guidelines. This may include placing it in a designated medical waste disposal bin.

*In the US, you can get a sharps container from most major pharmacies, with a safe return & disposal system supported by USPS.

What alternative is there to regular finger sticks for blood sugar testing?

Another method is continuous glucose monitoring (CGM), performed with a tiny sensor fitted to the arm attached to a transmitter that sends data to an app that an sit on a smartphone. Now the tech supporting CGM is more accurate and accessible, this is becoming increasingly popular with people who are non-diabetic, as well as diabetics who need CGM to monitor their glucose levels from hour to hour.

You can read more about CGMs in my blog: What’s the point of continuous glucose monitoring (CGM) for non diabetics?