Your Guide to Diabetes Supplies: Continuous Glucose Monitors
Managing diabetes can be exceptionally challenging. Constant glucose monitoring using a traditional fingerstick method is burdensome. Fortunately, advancements in technology and insurance coverage have made continuous glucose monitors widely available and accessible. In this post, we will explore continuous glucose monitors, how they work, their benefits, and how they can help improve the quality of life for those managing diabetes.
All About Continuous Glucose Monitors
What is a Continuous Glucose Monitor?
A continuous glucose monitor is a small device that measures glucose levels in a person’s interstitial fluid and sends this information to a receiver or smartphone. Continuous glucose monitors are used primarily by people with diabetes to monitor their blood sugar levels and help manage their diabetes more effectively. By seeing real-time data, people with diabetes can make informed decisions about food, exercise and medication dosages.
Continuous glucose monitors can also alert people when their glucose levels are too high or low, which can be life-saving, especially during sleep when low blood sugar levels can cause seizures or unconsciousness.
How do Continuous Glucose Monitors Work?
Continuous glucose monitors work by inserting a tiny sensor under the skin to measure glucose levels in real-time. The sensor is connected to a transmitter that sends data wirelessly to a device, such as a smartphone or insulin pump, which displays glucose readings and alerts.
The sensor measures glucose levels in the fluid between cells (interstitial fluid) rather than in the blood. Glucose in the interstitial fluid reflects blood glucose levels, but there can be up to a 15-minute delay in the readings.
Are Continuous Glucose Monitors Accurate?
Continuous glucose monitors are generally accurate, though not 100% foolproof. Accuracy largely depends on the type of device, calibration process, individual physiology and certain environmental factors.
Continuous glucose manufactures provide guidance on how to interpret and improve sensor accuracy. Both Dexcom G6 and G7 are factory calibrated for optimal accuracy at 100 mg/dL (plus or minus 20%). When a glucometer reads 100 mg/dL, a Dexcom sensor is a close match if it’s between 80 and 120 mg/dL. Freestyle Libre 3 is similar.
All continuous glucose monitoring manufactures will advise that patients confirm a low (<70 mg/dL) using the fingerstick method.
Accuracy of continuous glucose monitors can be compared by examining their MARD score (mean absolute relative difference). The MARD is a statistical measure of CGM accuracy; the lower the number the better.
Because continuous glucose monitors take a glucose reading every 1-5 minutes, they can provide a more accurate picture of glucose control when compared to 1-2 times daily fingersticks or A1c. This newer assessment of glycemic control is called Time in Range.
Will I Still Need to Prescribe a Blood Glucometer?
Yes! Patients using a continuous glucose monitor will still require a traditional glucometer to measure their blood sugar levels occasionally. Low glucose levels that are below 70 mg/dL should always be verified with a fingerstick. Additionally, high glucose levels above 400 mg/dL must also be measured using the fingerstick method. Patients may need to use a glucometer to measure their glucose during the sensor warm-up period.
Are Continuous Glucose Monitors Safe?
Yes! Continuous glucose monitors are considered safe and have been approved by regulatory bodies around the world, including the US Food and Drug Administration and the European Medicines Agency. Occasionally, skin irritation or infection may occur. However, these risks can be minimized by following the device’s instructions for use and proper site placement.
Are Continuous Glucose Monitors Painful?
No. Continuous glucose monitors are designed to be minimally painful. The process of placing a sensor can be slightly uncomfortable, but it is usually over quickly and should not cause pain. While, some people may experience irritation or discomfort at the site of the sensor, but this can often be alleviated by adjusting the location of the sensor or by using an adhesive patch to secure it in place.
Special Populations
There are special populations to consider when evaluating the appropriateness of prescribing continuous glucose monitoring.
Can a Patient Use a Sensor in Pregnancy?
Yes! Both the Dexcom G7 and Libre 3 are approved for use during pregnancy. Continuous glucose monitoring can be incredibly helpful in managing diabetes while pregnant, which can prevent complications for both the mother and baby. Pregnant women with diabetes are at a higher risk of preeclampsia, preterm birth, and birth defects, making tight glucose control essential.
Can a Patient use a Sensor while on Dialysis?
There is no definite answer as to whether a patient can use continuous glucose monitoring while on dialysis. Manufactures will advise against it. In practice—it’s used often.
Typically, a patient on dialysis has impaired kidney function, which may affect the accuracy of CGM readings. The changes in fluid balance during dialysis may also impact glycemic control. Some patients may have limitations that require them to disconnect the device before dialysis for safety reasons.
It is important to consider the benefits and risks of using CGM while on dialysis. Close monitoring of the CGM readings along with traditional blood glucose testing may help avoid hypoglycemic episodes. Minimize hypoglycemia is an import factor when being considered for a kidney transplant.
What About Young Children and Older Adults?
Continuous glucose monitoring devices are frequently used in the pediatric population. Dexcom G7 is approved for children as young as 2 years old. Libre 3 is approved for children as young as 4 years old. Though not approved, continuous glucose monitoring is often off-label in infants (neonates) to optimize glucose control while minimizing risk of hypoglycemia.
While there is no maximum age for continuous glucose monitoring use, advanced age does pose some unique challenges. Adaptation or acceptance of new technologies, insurance coverage, medication interference, and possible visual or motor impairments should be considered.
Family should be included in all new continuous glucose monitoring trainings. Many of the remote-compatible devices allow data sharing of data with parents or caregivers.
Continuous Glucose Monitoring Options
As of November 2023, there are several options available on the US market, including:
1. Dexcom G7 – a smartphone-compatible CGM that alerts users to highs and lows. The older model, Dexcom G6, is integrated with Omnipod 5, Tandem TSlim X2, and Beta Bionics iLet insulin pumps.
2. Freestyle Libre 3 – also smartphone-compatible CGM that alerts users to highs and lows. At a much lower price-point, Libre 3 is a great options for cash-pay users.
3. Medtronic Guardian 4 – a CGM with multiple alarms and customizable alert settings integrated with Medtronic’s 780G insulin pump.
4. Eversense 3 – a CGM that is implanted under the skin and lasts for up to 180 days.
You can view a full comparison of key features across each model in the chart below.
Prescribing a Continuous Glucose Monitor
Are Continuous Glucose Monitors Covered by Commercial Insurance?
Yes, continuous glucose monitors are covered by many commercial insurance plans. Some plans may require prior authorization or have requirements for the type of therapy the patient must be using (i.e., insulin use, number of injections per day, etc.). While most commercial insurances will dispense sensors at the local pharmacy, some plans require the patient to use a mail-order pharmacy or a durable medical equipment (DME) supplier.
Are Continuous Glucose Monitors Covered by Medicare?
Yes, Continuous Glucose Monitors are covered by Medicare for beneficiaries who meet certain criteria. Medicare covers sensors for individuals who meet the following requirements (as of November 2023):
- Must have a diagnosis of diabetes.
- Sufficient training on how to use the prescribed device.
- Prescribed in accordance with its FDA indications for use.
- Must meet at least one of the following criteria;
- Insulin-treated; or,
- A history of problematic hypoglycemia with documentation of recurrent low-events (glucose <54mg/dL) despite multiple attempts to adjust the diabetes treatment plan; or,
- A history of a “level 3” hypoglycemic event, defined as a glucose <54mg/dL with altered mental and/or physical status requiring third-party assistance.
- An in-person or telehealth visit with within the last 6 months with the treating practitioner.
Continuous glucose monitors are considered durable medical equipments and will need to be ordered through a DME-supplier.
Are Continuous Glucose Monitors Covered by Medicaid?
It depends. In Colorado—yes, if the beneficiary meets certain criteria. The Center for Health Care Strategies maintains an updated list of state Medicaid coverage guidelines.
What if Continuous Glucose Monitors are Not Covered?
When continuous glucose monitors are not covered by insurance, patients may choose to pay for the devices themselves. Many of the manufactures offer financial assistance programs.
Key Takeaways
Managing diabetes can be a challenging task, particularly with traditional fingerstick glucometers. However, the rise of continuous glucose monitors has significantly reduced the burden of diabetes self-care.
Continuous glucose monitors are affordable, accessible, relatively pain-free, and very easy to use. Despite some accuracy concerns, continuous glucose monitors provide an incredible volume of data, as well as life-saving alerts and alarms that prevent against dangerous low glucose values.
Managing patients on continuous glucose monitors may feel daunting, but the improvements in quality of life and overall health outcomes far outweigh any administrative burdens.
