Takeaways:

• A CGM requires only one needle stick each time you put on a new sensor, while a traditional glucometer requires several finger pricks per day.

• With a glucometer, you need to test several times a day; while, a CGM is worn full-time and measures sugar levels on an ongoing basis.

• A glucometer tests the sugar levels in your blood, while a CGM tests the levels in interstitial fluid, which is the fluid between cells in your tissues.

• Traditional glucometers require that you have a reliable supply of test strips. Meanwhile, with a CGM, you only have to change sensors every 10 or 14 days.

• Because a CGM monitors blood sugar continuously, it helps to ensure that you catch high and low blood sugar events. With a traditional glucometer, if you don’t happen to be testing during the time when these events happen, you could easily miss them. 

• A CGM also allows you to identify patterns and trends in your blood sugar levels. A traditional glucometer only tests at a few discrete points in time, so you have a lot less information about how your blood sugar changes over time.

For people with diabetes, monitoring blood sugar levels regularly is crucial for protecting your long-term health and reducing the risk of serious health issues. The traditional method of testing blood sugar has been to use a glucometer. This device uses a drop of blood obtained by finger prick, which is placed on a test strip and inserted into the glucometer to determine your blood sugar level. 

More recently, continuous glucose monitoring, or CGM, has been developed as an alternative. This method uses a wearable device to check blood sugar continuously. How can you decide whether to use a glucometer or CGM to test your blood sugar? What factors should you consider when making this choice?

Why is it important to monitor blood glucose?

For people with diabetes, monitoring blood sugar is very important. 

High blood sugar causes damage to tissues throughout the body, including the eyes, kidneys, nerves, and blood vessels. The more often a person’s blood sugar rises too high, the more likely they are to experience major complications related to this damage, such as loss of vision, kidney failure, and nerve damage.

When the blood sugar rises extremely high, this can lead to a condition known as ketoacidosis, which can cause a person to go into a coma and can even lead to death.

At the same time, low blood sugar is also a risk for people with diabetes. Low blood sugar can affect the brain, causing a person to feel confused and dizzy. In severe cases, it can lead to seizures and an irregular heartbeat, and can also potentially be fatal.

It’s crucial for people with diabetes to keep an eye on their blood sugar, and to keep it in the normal range as often as possible. This helps to prevent the long-term complications of diabetes, and also avoids the potentially fatal consequences that very high or very low blood sugar can cause.

What causes blood sugar to be high or to be low?

The body of a person with diabetes either doesn’t make enough insulin, or the cells don’t respond normally to insulin. Insulin is a hormone that keeps blood sugar levels from rising too high. This is why people with diabetes tend to experience high blood sugar levels, or hyperglycemia. 

Episodes of high blood sugar may occur when you aren’t taking a high enough dose of diabetes medication, or when you eat too much or snack between meals. Stress, illness, and injuries can also cause your blood sugar to rise, because stress hormones stimulate an increase in blood sugar.

The most common cause of low blood sugar, or hypoglycemia, is treatment for diabetes. Insulin and oral diabetes medications can both lead to low blood sugar. If you don’t eat as much as usual, or if you skip a meal or eat later than usual, then your blood sugar may drop. Exercise can also decrease blood sugar. Drinking alcohol interferes with the liver’s release of glucose, and can also lead to low blood sugar. If you’re experiencing frequent episodes of hypoglycemia, then your medication plan may need to be adjusted to help prevent this from happening.

How is blood glucose measured?

The traditional way of measuring blood glucose is to use a device called a glucometer. You prick your finger, and apply a drop of blood to a test strip. This is treated with chemicals that react with sugar in the blood. The strip is then inserted into the glucometer, which looks for the products of the chemical reactions to determine what your blood sugar level is.

Until recently, this was the only option for measuring blood sugar. People with diabetes had no choice but to do this multiple times every day, in order to achieve good blood sugar control. (Blood sugar can also be measured in the laboratory, but this is an unrealistic option for everyday glucose measurements.) There are still many people who use this option for blood glucose testing, but there is now another option available.

The evolution of blood sugar monitoring devices

Because of the discomfort and hassle associated with the traditional method of blood glucose testing, it was difficult for people to test their sugars as often as needed to stay healthy. Some people with diabetes would even avoid testing their sugars, because of how painful it can be.

The invention of continuous glucose monitoring (CGM) devices has made a huge difference in the lives of many people with diabetes. CGMs use a small wearable sensor, which is usually applied on the abdomen or the arm. The sensor measures blood sugar on an ongoing basis. The data is transmitted from the sensor to a person’s smartphone. For those who don’t have a smartphone, some CGMs have a handheld reader available as an alternative.

A CGM sensor is worn full-time. The sensors are designed to be waterproof, so it’s easy to shower or exercise while wearing them. The sensor needs to be removed and replaced periodically, usually every 10 to 14 days. The new sensor is placed in a different location than the old one, to allow the skin in that area time to rest and heal.

If you’re using a CGM, some models provide alert functionalities whenever your blood sugar goes too high or too low. 

When is the best time to test?

If you’re using a traditional glucometer, then you’ll need to test several times a day. Testing is usually recommended:

• Before you eat

• Before and after you exercise

• Just before bed

Testing about two hours after meals may also be recommended in some cases. Those who tend to experience hypoglycemia at night may also need to test in the middle of the night. You may also need to do additional testing if you change your daily routine, if your medications are changed, or if you get sick.

With this method, you have to actively choose to test your blood sugar. It can be easy to forget, and it can also be easy to avoid testing when you feel that your blood sugar is likely to be too high. In addition, low blood sugar can cause symptoms like confusion, making it hard for users to remember that they should test and to focus well enough to do it correctly.

How do you choose a glucometer that’s right for you and your lifestyle?

For people with diabetes, there are a few things to consider when you’re deciding how to monitor your blood sugar.

• CGMs are more convenient, because they monitor your blood sugar automatically and are worn on the body. You don’t have to think about testing your blood sugar, and you don’t have to remember to bring your glucometer and test strips with you whenever you leave the house.

• A CGM requires only one needle stick each time you put on a new sensor, while a traditional glucometer requires several finger pricks per day.

• Because a CGM monitors blood sugar continuously, it allows you to identify patterns and trends in your blood sugar levels. A traditional glucometer only tests at a few discrete points in time, so you have a lot less information about how your blood sugar changes over time.

• Traditional glucometers require that you have a reliable supply of test strips. If you run out of these, you won’t be able to test your blood sugar until you get more of them. With a CGM, you never have to worry about running out of test strips.

• CGMs tend to cost a bit more than traditional glucometers. Patients on an extremely strict budget may choose a glucometer for this reason. Certain insurance plans will cover a CGM, but not all. There are also ongoing costs with both options; with a glucometer, you’ll need to purchase test strips regularly, while with a CGM, you’ll need to purchase replacement sensors regularly.

• A glucometer tests the sugar levels in your blood, while a CGM tests the levels in interstitial fluid, which is the fluid between cells in your tissues. Although these levels are highly correlated, it takes a few minutes for changes in your blood sugar level to show up in your interstitial fluid. This means that when your blood sugar level is changing rapidly, a CGM will be a few minutes behind a glucometer in detecting the shift. Most of the time, this isn’t a problem, but sometimes it may be important. For example, if you have symptoms of low blood sugar, but your CGM isn’t showing it, then you should test with a glucometer. Your blood sugar may have dropped very rapidly, and it hasn’t yet shown up on the CGM.

Who should use a CGM?

There are certain groups for whom a CGM is more strongly recommended. These include:

• People who have hypoglycemia unawareness. This means that you don’t experience significant symptoms when your blood sugar drops. A CGM can help you to avoid dangerous hypoglycemia events by alerting you when your sugar level is dropping.

• People who frequently experience high or low blood sugar events. A CGM can help to achieve better blood sugar control by alerting you when your blood sugar is trending too high or too low, so you can take action.

• People who are using short-acting insulin, which is injected several times per day or infused through an insulin pump. This includes people with type 1 diabetes, and some people with type 2 diabetes. 

People with type 2 diabetes who are not using insulin, or who are only using basal (long-acting) insulin, may not necessarily need a CGM. However, they might still prefer to use one, to help gain better insight into how various lifestyle choices affect their sugar levels or to help avoid possible hypoglycemia events. For these people, the decision of whether to use a CGM or a traditional glucometer is a personal choice.

What are the current options on the market?

There are a number of different glucometers currently available in Singapore. If you’re interested in a CGM, there are two main options currently available in Singapore: the Dexcom G6, and the FreeStyle Libre. Both of these can work with a smartphone, and will alert you when your blood sugar is going too high or too low. 

The two systems are fairly similar in many ways, although the Dexcom G6 requires replacing the sensor every 10 days, while FreeStyle Libre allows you to go 14 days before replacing it. The cost is also a little different. In general, both of these systems are great ways for people with diabetes to monitor their blood sugar, and we offer both of them to our patients here at NOVI Health. 

Explore which CGM is right for you in this article. Dexcom G6 and Abbott FreeStyle Libre are comparable, yet the two systems differ in several key ways, which users must consider when choosing between them.