The Continuous Glucose Monitor Reinvented
Blood glucose monitoring is a critical component of diabetes management, especially for people with type 1 diabetes and for those who take insulin. It makes diabetes management easier, but can be an intensive process. Continuous glucose monitors can make it easier, and there is now more than one option available in the United States market: the FreeStyle Libre Flash Glucose Monitoring System was approved for use.
Why Monitoring Is Important
The American Diabetes Association suggests that most patients using intensive insulin regimens, such as multiple insulin injections or insulin pump therapy, perform self-monitoring of blood glucose (SMBG) prior to meals, snacks, and exercise, at bedtime, occasionally after meals, when they suspect low blood glucose, after treating low blood glucose until their blood sugar has reached a normal level, and prior to critical tasks such as driving.It has been reported that those people who test their blood sugar more often have lower A1Cs and less glucose variability. But, you can imagine how intensive this can be—multiple finger stick checks can be time-consuming and difficult to manage.
Continuous Glucose Monitoring
In addition to SMBG, many people with diabetes decide to use a continuous glucose monitor (CGM) to retrieve more information about their blood sugars so that they can better manage their medicine, exercise, and food.
To date, CGMs can provide glucose readings roughly every five minutes and include sophisticated alarms that tell a person when their blood sugar is trending low or high. Studies have shown that CGM use is associated with lower A1Cs, fewer missed school days, and reduced frequency of hypoglycemia.
Using a CGM can make glucose management easier, but not without finger sticks. All CGMs must be calibrated with a blood glucose test, which doesn’t solve the problem of intensive blood sugar testing. But, the good news is that new tools are always being researched and approved.
How It Works
The Freestyle Libre System uses the latest technology to provide real-time glucose readings every minute using a pre-calibrated sensor (you do not have to calibrate it with a finger stick, this is done in the factory). Unlike other CGMs, there is no bulky transmitter; instead, the small, water-resistant sensor (roughly the size of a quarter) is inserted easily five millimeters under the skin into the back of the arm. The sensor measures the interstitial fluid, which is comparable to capillary blood.
After a twelve hour startup period, you can retrieve a blood glucose reading simply by scanning the sensor with your Reader. You can scan as often as you’d like, but, in order to capture all data, it is recommended that you scan your sensor at least once every eight hours to record 100 percent of the data. Studies conducted by Abbott have demonstrated that people who use this sensor wind up scanning more often than testing their blood sugar with a finger prick, which provides them with more valuable data.
The Libre has the ability to store 90 days worth of data. It can be worn up to 10 days—it stops working after this time period and must be replaced. Once you are finished with your sensor, you can dispose of it.
The Libre also has a blood glucose meter within the system. You might be thinking to yourself, why would I test my blood sugar if my CGM is checking it every minute? For starters, you might be curious if the CGM is accurate. In addition, there are certain times when the CGM can yield inaccuracies—this may be during a rapid change in blood glucose, such as after eating, dosing insulin, or exercising. Severe dehydration and excessive water loss may also cause inaccurate results. During these times, you’ll want to confirm your blood sugar with a finger stick.
Additionally, if you are having symptoms of low or high blood sugar, you should check your blood sugar manually (because the Libre has no alarms). The strips used in the meter are called Precision Neo test strips. They are an inexpensive, cash pay strip, individually foil wrapped so they can be used until the expiration date. Typically, a box of 50 costs about $20. Using other test strips with the built-in meter will produce an error or cause it to not turn on or start a test. You can not use the meter to test for ketones.
Sometimes, the Reader will not be able to let you know where your glucose is trending and will provide you with a warning symbol. Whenever you see this symbol, you should do a blood glucose test and treat based on that result.
Freestyle Libre is the first and only CGM that eliminates finger sticks for calibration. Instead of checking finger sticks multiple times per day, persons with diabetes can scan their CGM (a painless procedure) to get real-time glucose readings that they can use for insulin dosing, meal planning, etc.
For those people who loathe testing, this could help them to better manage their diabetes, all while improving their quality of life. In addition, large amounts of data and trend reports can help people with diabetes reduce their risk for low blood sugar and help them to figure out insulin dosing and meal planning.For those people with diabetes that could not afford other CGMs, the Libre System may provide them with a solution.
Comparing to Other Devices
The Libre device is referred to as a flash glucose monitoring system. As compared to other CGMs like the Dexcom G4 and G5, the Libre system checks glucose every minute rather than every five minutes and it can be worn for 10 days, as opposed to seven. It is very accurate and does not require finger stick calibrations. Because the Libre does not require a transmitter, the price for it and its sensors has been lower compared to other CGMs.
Another difference is that Libre does not have any automatic alarms—potentially to avoid alarm fatigue. You can still detect a high or low blood sugar, but only after scanning your device. If at that time you’ve identified an abnormal blood sugar, the Reader will alert you and prompt you to set a reminder to scan again.Lastly, Sensor placement is not approved for sites other than the back of the arm (other CGMs are approved for belly and buttocks placement). If placed in other areas, the Sensor may not function properly.
Storage is important to protect the sensor and keep the glucose readings as accurate as possible. Avoid freezing the sensor kit and store the kit between 39°F and 77°F. You don’t need to keep your sensor kit in a refrigerator, but you can as long as the refrigerator is between 39°F and 77°F. Store the sensor kit between 10 to 90 percent non-condensing humidity.
One of the biggest limitations is that there are no alarms without a sensor scan. The Libre System will not automatically alert you if your blood sugar is very high or very low unless you scan your sensor. For example, the System will not alert you if your blood sugar is low when you are sleeping. Additionally, the Libre has not been evaluated for use in people with hypoglycemia unawareness.The Libre system is also not indicated for use in anyone less than 18 years of age.
Freestyle Libre Pro
The FreeStyle Libre system is different from the Freestyle Libre Pro. Abbott’s FreeStyle Libre Pro system is meant to provide clinicians and patients with information about blood glucose readings for a 14-day period. It is used temporarily to help make treatment decisions for people with erratic blood sugars or frequent hyper- or hypoglycemia.
During the time the patient wears the sensor, they are not required to have interaction with the device nor do they have to draw blood via a finger stick to calibrate the sensor. But, they must continue to test their blood sugars and keep a log of their sugar, food, exercise, etc.After 14 days, the patient returns to the doctor’s office, where the doctor uses a FreeStyle Libre Pro reader to scan the sensor and download the 14-days’ worth of glucose results that are stored in the sensor—in as little as five seconds.
A Word From Verywell
The Freestyle Libre Flash Glucose Monitoring System is the first CGM to eliminate finger stick calibration. This is exciting news for people with diabetes.One major difference to consider before discussing this with your physician is that the Libre System does not have built-in alarms and is not meant for patients younger than 18 years of age. Eligible patients with diabetes must receive a prescription to get this meter. If you think you are eligible or are interested, ask your health care team about it. If you have any doubts, you can always see if you can trial the Freestyle Libre Pro before getting started.