Measles Information

A continuous glucose monitor on a person's upper arm.
A continuous glucose monitor on a person's upper arm.

How Do Continuous Glucose Monitoring Systems (CGMS) Work?

And Should You Get One?

People with diabetes need to constantly monitor their blood glucose (sugar) levels to make sure that they’re not too high or too low. If your levels are too low (hypoglycemia), they can impact your ability to think and function. If they’re too high (hyperglycemia), they can cause damage to your organs over time.

Monitoring your blood glucose levels used to involve pricking your finger multiple times a day for a blood sample, which was then read by a device called a glucometer. This was not only inconvenient, but also only provided a snapshot of glucose levels at one point in time.

Continuous glucose monitoring systems (CGMS) are changing the state of diabetes care.

“CGMS are not just better, more accurate glucometers,” says Jyothi Gogineni, MD, a Northwestern Medicine endocrinologist. “They provide real-time data and can predict glucose changes and patterns over time.”

Benefits of Continuous Glucose Monitoring Systems

CGMS can:

  • Alert you if you’re experiencing hypoglycemia or hyperglycemia. Hypoglycemia can be very dangerous as it can lead to loss of consciousness. If you can detect it early, you can treat it early by eating foods or drinking beverages high in sugars or carbohydrates.
  • Show you trends in your blood sugar, which can help your healthcare team make more meaningful adjustments in your diabetes medications, if you use them. Most CGMS also allow you to share your blood glucose levels with your healthcare team in between appointments to optimize your treatment.
  • Show you how you need to modify your behavior. They will show you in real time what types of foods and meals will spike your blood glucose, which will help you know what foods to eat in moderation or to balance with protein. They can also show you how exercise impacts your blood sugar.
  • Give you a sense of control. They can also help reduce the fear of hypoglycemia, which is very common among patients on insulin, a medication that helps stabilize blood glucose.
  • Reduce family worry. Many CGMS allow you to share your blood glucose information with family members to help ease any worries about your health.

How Do Continuous Glucose Monitoring Systems Work?

You wear a CGMS a patch on your body. The device has three parts: a sensor, transmitter and receiver. The sensor goes into your skin to measure the glucose level in your interstitial fluid, which is the fluid that surrounds the cells below your skin. Glucose moves from blood vessels into your interstitial fluid, so the levels of glucose in your blood and interstitial fluid are very similar. The sensor detects the glucose level in your body every few minutes, and then the transmitter sends the information to a receiver, which is typically either an app on your smartphone, a receiver or an insulin pump worn on your body. You have to replace the sensor every 10 to 14 days.

“CGMS devices are getting smaller; the interface technology is improving,” says Douglas L. Ambler, MD, Northwestern Medicine internal medicine physician. “The data can more easily be sent to your physician to inform your care.”

Who Should Get a Continuous Glucose Monitoring System?

Anyone can pay for a CGMS but it requires prescription from a clinician. CGMs are typically ordered by your clinician through a referral to the diabetes center and often covered by insurance. If you are interested in a personal or professional CGM, talk to your primary care clinician.

What Can a Continuous Glucose Monitoring System Tell You if You Don’t Have Diabetes?

A CGMS can tell you how your body reacts to certain types of foods and exercise. You may see that certain foods cause a bigger increase in blood glucose, and you may also see how certain types and duration of exercise have a positive impact on your blood glucose.

Ultimately, this can tell you if you are prediabetic, which means your blood glucose is higher than normal but not yet high enough for you to be diagnosed with Type 2 diabetes. Prediabetes increases your risk of developing Type 2 diabetes, heart disease and stroke.

Learn more about the types of diabetes.