How to Properly Check Blood Sugar – Why and When, A Guide

Posted by Prescription Hope - See Editorial Guidelines (Last Updated On: Tue Apr 25 2023)

Monitoring and keeping track of your blood sugar levels is crucial for managing your diabetes condition. Properly checking blood sugar levels will give one a clear understanding of what they need to change in their treatment regimen to better control their condition.

So, in this article, we will discuss how to properly check blood sugar and errors that could go wrong while testing. First, here is a quick answer to give you a basic understanding before we get into more details.

How to Properly Check Blood Sugar: Checking your blood sugar is often done using a glucose meter, lancet device, and test strips. Individuals should wash their hands first, then insert the test strip into the glucose meter. Next, you prick your finger with the lancing device and apply blood to the test strip. Those with type 1 diabetes need to check their blood sugar many times throughout the day at specific times, and those with type 2 may only need to test a couple of times a day if that.

Now that you have the basic answer, here is more detail about how to properly check blood sugar.

Why You Need to Test Blood Sugar

Properly Check Blood Sugar

Individuals that are struggling with diabetes will be required to check their blood sugar in order to control their condition. Patients dealing with this condition will often suffer from hyperglycemia and even hypoglycemia at times. So, they have to follow a treatment regimen to try and keep their blood sugar levels between 70-120 mg/dL.

However, one of the only ways to determine one’s blood sugar level is through a finger prick test.

The test will help patients make daily treatment decisions. The results will give a person a better idea of how foods impact their glucose levels, if their condition is uncontrolled from an illness, and how other factors affect their health.

Not having your blood sugar levels controlled can result in serious long-term consequences. Therefore, knowing how well you are controlling your condition by properly checking your blood sugar is crucial.

When to Test

When exactly you need to test your blood sugar will vary from person to person. Below are recommendations for when you should properly check blood sugar levels, based on the specific type of diabetes that you have.

Type 1

Those that have type 1 diabetes will need to check their blood sugar levels often, as they have to control their condition with insulin. As someone that has diabetes, I check my own glucose levels up to 8 times a day. The list below will give you a good idea of when it is important to check your blood sugar.

  • In the morning when you wake up
  • Before each meal or snack
  • Before and after exercising
  • Before going to bed
  • If you ever feel nauseous, lightheaded, or abnormal in any way
  • More often if you are sick
  • More often if you are starting a new medication or changing your treatment regimen
  • During the night if you are continuously waking up with high blood sugar

Type 2

Many individuals with type 2 diabetes can manage their condition with oral medications along with diet and exercise. However, if you require insulin therapy, your doctor may recommend checking your blood sugar more often.

If you are only using long-acting insulin to manage your condition, then checking your blood sugar once in the morning and once at night should suffice. Otherwise, you may only need to check your blood sugar every couple of days to ensure the medications you are taking are continuing to work.


Typically, doctors recommend checking your blood sugar first thing in the morning and about two hours after each meal if you have gestational diabetes. If your blood sugars become out of control during pregnancy, then it may harm your unborn baby.

It is important to note here that you should follow your doctor’s advice for when you should check your blood glucose levels.

How to Properly Check Blood Sugar

Checking your blood sugar can seem very simple, but it must be done properly. Not testing your blood glucose levels in the right way can result in inaccurate readings. Inaccurate readings can cause you to mistakenly make the wrong treatment decision, which can be life-threatening in some scenarios.

Wash and Dry Hands

Before ever touching your glucose meter or test strips, you must wash and dry your hands. Doing this will not just prevent infections but prevent inaccurate glucose readings.

Insert Test Strip into Meter

After washing your hands, you will then take a test strip from its container and insert it correctly into the glucose meter. It is crucial that you have the right test strips, as they must be compatible with the glucose meter. You can ask your pharmacist to ensure you are buying the right test strips.

Prick Your Finger

Most glucose meters will come with a lancing device. The device has lancets that should be replaced after each use. Use the lancet device to prick the side of your fingertip (follow the manual that came with your glucose meter to learn how to use the lancet device). You may need to squeeze your finger around the area you pricked to get blood. Apply the blood to the appropriate place on the test strip.

Take Appropriate Action

After applying the blood to the test strip, the meter will display your blood sugar reading. You can then make appropriate treatment decisions based on your glucose reading.

When You Use a CGM

Many patients, particularly those with type 1 diabetes, use continuous glucose monitors (CGM). So, if you use a CGM, do you need to check your blood sugar via pricking your finger?

The answer to this is yes, but you may not need to check your sugar as often. Certain CGMs will require you to calibrate it at least twice a day, in which you will need to properly check blood sugar. CGMs are also not always 100% accurate, as they measure the glucose in the interstitial fluid, instead of glucose in the blood.

Therefore, it is highly recommended that you check your blood sugar if you ever feel abnormal or if you believe your CGM is not accurate.

What Affects Test Results

A major reason why we have discussed, properly checking blood sugar, is that various factors can affect the test results.

The first and most prominent factor is having residue on your fingers or hands. If you have residue from food on your finger when you are checking your blood sugar, then that can mix with your blood, giving you an inaccurate reading. It will more than likely give you a blood sugar reading higher than what it actually is.

This can be very dangerous because if you choose to inject insulin to correct that “high,” then you may potentially have a severe low blood sugar event. Low blood sugar that is not immediately treated can lead to seizures, consciousness, and even death. Thus, it is why it is highly recommended that you wash your hands prior to testing.

After washing your hands, you should ensure that your hands are completely dry. Having wet hands when you test your blood sugar can dilute your blood. This can cause inaccurate results or an error message on your glucose meter.

Another factor that can cause inaccurate results is test strips that are expired or damaged. Expired test strips or strips that have been exposed to extreme temperatures or moisture can affect your blood sugar readings. Ensure that the strips you are using are stored correctly and are not expired.

Lastly, as part of properly checking blood sugar, ensure you calibrate your glucose meter regularly. Glucose meters can sometimes lose their accuracy over time and require calibration without warning. The manual that came with your meter will provide you with methods on how to do this, as it is specific to the glucose meter you are using.


We hope this given you a better understanding of how to properly check blood sugar and why. Always consult your doctor for specific questions regarding your condition.

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