BGL testing and monitoring

Testing Blood glucose levels (BGLS) helps you manage your diabetes. Your doctor and diabetes educator will tell you how often to test and when to test. Most teenagers test before meals, before bed, when they’re playing sport or feeling unwell. Not everyone with diabetes does all of these tests, your diabetes team will let you know what tests you should be doing.

Some people think they don’t need to test or that they can guess their BGL depending on how they’re feeling. We know that this doesn’t really work and can put you at risk of problems like hypos or high BGLs and ketoacidosis (DKA) if you get it wrong. It can also make it hard for your doctor to adjust your insulin if they don’t have any accurate BGLs.


To test your BGL you need a blood glucose meter. There are lots of different meters for you to choose from. You can download information from some meters on to a computer so you can see what your BGLs are doing from day to day. Talk to your diabetes educator about the different meters available.

It’s important to look after your meter so that it works properly. Try to keep it clean, don’t drop it and make sure it doesn’t get too hot or cold. There are special packs you can buy to protect your meter in hot or cold places.

Finger Prickers/Lancets

A finger pricker or lancet is used to get the drop of blood to test your BGL. There are lots of different types and you can change how deep they go into your finger or skin so that it doesn’t hurt too much. When you prick your finger, try to do it on the sides at the top of your finger not on the soft part at the tip or your fingers will get very sore. It’s also important to change where you do your finger prick each time. Don’t forget to change the lancet (sharp bit) of your finger pricker before it gets blunt otherwise it might hurt or not work properly. Always dispose of your used lancets in a recognised sharps container.

Alternate Site Testing

Some meters let you use the blood from different parts of the body to test BGLs. These include the forearm, base of thumb, thigh and calf. You need a special lancet that goes with the meter. You can’t do alternate site testing with a regular meter or lancet. There may be some difference in BGL results if you use alternative sites. This is because the blood flow to your hands is faster than it is to these other sites which means that differences in BGL readings could delay picking up a hypo.

Blood Glucose Test Strips

There are special testing strips that you need to use with your blood glucose meter. Once you’ve obtained a drop of blood, place it on the testing strip. Some strips need more blood than others, and these days most strips suck up the blood from the point of contact. Every meter has its own testing strips that you use once and then throw away carefully (wrap in test strip cover or within a tissue).

Everyone with diabetes should join the National Diabetes Services Scheme (NDSS) to be able to buy cheaper strips.

Ketone Testing

When your BGLs are high (more than 15 mmol/L) or when you’re sick it’s important to test for ketones. Ketones are a sign that things are out of balance and you may be at risk of diabetic ketoacidosis (DKA). There are two ways you can test for ketones – by testing your blood or by testing your urine.

Blood – There are meters you can get to test your blood for ketones. You can use the same drop of blood to test your BGL and test for ketones, so you only need to prick your finger once. There are different strips to test your BGL and for testing ketones.

Urine – If you don’t have a meter that tests for ketones, you need to test your urine (wee) for ketones. There are special strips for this. To do this test, wee on the strip when you go to the toilet. It might sound gross, but it’s really important.

Continuous Blood Glucose Monitoring (CGMS)

There are meters that allow for continuous monitoring of BGLs by using a small sensor placed just under the skin. These monitors are not designed to replace your usual meter, but may be used for short periods of time to assess what’s happening with BGLs. There are also CGMS devices that can be used in conjunction with some of the insulin pumps available. Ask your diabetes educator for more info.

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