Continuous glucose monitoring (CGM) devices help you manage Type 1 or Type 2 diabetes with fewer fingerstick tests. A sensor just under your skin measures your glucose levels 24 hours a day. A transmitter sends results to a wearable device or cell phone. It takes time to learn how to use CGM, but it can help you more easily manage your health.
Continuous glucose monitoring is wearable technology that makes it easier to track your blood sugar levels over time. Blood sugar is another term for blood glucose.
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CGM is a tool for people with diabetes. It measures your glucose levels 24 hours a day when you are wearing the device.
Insulin is a hormone that helps your body regulate blood sugar levels. If you have Type 1 diabetes, your body doesn’t produce enough (or any) of the hormone insulin. In Type 2 diabetes, your body makes insulin but doesn’t use it effectively.
People with diabetes need to give themselves insulin regularly to keep blood sugar levels steady.
Tracking blood glucose levels tells you how much insulin your body needs and when. Blood sugar levels that go up and down a lot can damage your body in different ways. Very high (hyperglycemia) or low (hypoglycemia) blood sugar levels can be serious, and even life-threatening when not treated quickly.
Many things (like the foods you eat, sports you play and your lifestyle) can affect your blood sugar levels. But diabetes affects everyone differently. How a food or activity affects one person’s glucose levels is often different from how that same thing affects someone else.
Your body can also be unpredictable. Sometimes, your body can have a reaction that even healthcare providers don’t always understand. All of these factors can make managing diabetes challenging, even when you think you’re doing everything right.
You can regularly check your blood glucose levels using a fingerstick blood check and a blood glucose monitor. Many people do just that.
But fingerstick checks only measure blood glucose at one moment in time. It’s like reading one page of a book. Doing more fingerstick checks gives you more snapshots, which can offer clues to what’s happening with your blood sugar levels.
You can choose among a handful of CGM devices available today. Each works pretty much the same way. The main differences are in a device’s look, feel and features.
In general, here’s how CGM works:
CGM devices are complex little machines. They do require some upfront time to understand their technical aspects.
For example, you will need to learn how to:
It takes time and patience to understand how a CGM device works. But you don’t have to do it alone. Your provider will need to prescribe a CGM device (much like any medication).
Once you have a CGM, a qualified professional helps you learn how to use it safely. Your provider may recommend taking a diabetes education class or speaking one-on-one with a certified diabetes educator (an expert in diabetes tech).
Using a CGM device can make it easier to manage Type 1 or Type 2 diabetes. Some people use CGM for a week to understand their blood sugar patterns. Most use CGM long-term.
A CGM device can:
CGM is not a cure for diabetes. It's a tool (and not one you can set and forget). You need to actively use CGM for it to be helpful. But once you get the hang of how to use it, CGM may help you better manage your blood sugar levels and overall health in less time.
No. Fingerstick checks will still be an essential tool for you to manage diabetes.
Because fingerstick checks measure glucose levels in your blood, they provide the best picture of what your glucose level is at the precise moment you take it. CGM measures glucose under your skin, which shows where your glucose levels were five to 10 minutes ago.
With diabetes, certain things can make glucose levels rise or fall quickly. Big or fast changes in blood glucose levels can be dangerous. Doing a fingerstick check can provide important information to help you take action to protect your health. It can also act as a backup tool to confirm CGM results.
You may need to do fingerstick checks to calibrate (set up or adjust) a CGM device. Either way, you’ll likely still need to do fingerstick checks to look at your blood glucose in certain situations.
For example, a fingerstick check may give you peace of mind if your CGM device shows rising or falling numbers, but you feel OK. It can also provide answers if you don’t feel well, but the CGM says your glucose levels are in target.
Reach out to your provider if you have any questions about how to use a CGM device safely.
Very high or low blood sugar levels can be dangerous when left untreated for too long. In the most severe cases, this can lead to seizures, coma or even death. You can avoid these complications by keeping blood sugar levels in a healthy range. Call your provider if you have any symptoms you’re worried about.
Common symptoms of high blood sugar include:
No, CGM devices and insulin pumps are not the same.
They do very different things:
But they are similar in some ways. Both CGM devices and insulin pumps are:
Yes, many people use both a CGM device and an insulin pump. But you can also choose to use one and not the other (a CGM device or an insulin pump).
While both devices offer unique benefits, CGM systems and pumps that work together can offer additional benefits. Some pumps will make certain insulin delivery adjustments automatically based on data from a CGM. Even these joint systems still require user input and management but can offer an added level of safety and a quicker response to increasing and decreasing glucose levels.
CGM devices can be expensive. More and more insurance providers cover them today, which may make the cost more affordable. Your health insurance policy may only cover certain CGM devices.
Keep in mind that you’ll need to replace sensors and possibly transmitters regularly. Check with your insurance provider to see what devices and supplies your plan covers. Many providers and CGM companies have resources to help make CGM more affordable for those who need it.
A note from Cleveland Clinic
Learning how to use a CGM device can take time. It’s not a diabetes cure or a quick fix. But it has the potential to help you better understand the disease. A CGM device lets you keep a closer eye on glucose trends (instead of individual glucose numbers). By seeing the bigger picture, you can prevent problems or catch them early on to better manage your health. CGM’s automated, “always-on” setup may give you more freedom, flexibility and peace of mind. It could also help you focus on other things without worrying about your blood sugar as much.
Last reviewed by a Cleveland Clinic medical professional on 07/07/2021.
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