Continuous glucose monitoring (CGM) uses a sensor that is implanted just below the surface of the skin to detect blood sugar levels without finger sticks. Because most CGM devices take readings at regular intervals, they give a more complete picture of blood sugar trends over time than traditional finger-stick, self-monitoring methods. CGM can provide insight into how meals, exercise and illness impact blood sugar levels, help prevent blood sugar spikes and dips, and minimize the guesswork that comes with making treatment decisions. Studies have shown that some CGM systems may help reduce A1C levels (average blood sugar over three months) and the risk for hypoglycemia.
With all of these benefits, many people with diabetes are interested in using CGM to help manage their blood sugar. There are many CGM devices from which to choose, so we’ve broken down the options based on functionality, cost and personal preference.
Available CGM Devices
The Dexcom G6 is a CGM device that can provide up to 288 readings per day (every five minutes). The sensor and transmitter are worn on the abdomen, and readings are automatically sent to the receiver or a smartphone (in the Dexcom app). The sensor is water-resistant and must be changed every 10 days, but the transmitter lasts for three months. The G6 is factory-calibrated, meaning it requires fewer finger sticks. The system offers customizable alarms for high and low blood glucose and voice integration with Apple’s Siri technology.
Abbott’s Freestyle Libre is in its own category as a flash glucose monitor. It does not automatically send blood glucose readings to the receiver. Instead, wearers must swipe the receiver or their smartphone with the LibreLink app over the sensor to get glucose readings. The transmitter is built into the sensor. The sensor is worn on the back of the arm for 14 days, and it can be scanned through clothing. It is also water-resistant. The sensor is factory-calibrated, requiring fewer finger-sticks. There are no alarms for high or low blood sugar.
The Medtronic Guardian Connect can be used on its own or with the Medtronic Insulin Pump. The sensor can be worn on the upper arm or abdomen for seven days, and wearers use their smartphone with the Medtronic app as a receiver. The Guardian Connect can predict where blood glucose levels are headed and can alert users 10–60 minutes before a significant blood sugar spike or dip. Daily finger sticks are required for calibration.
The Senseonics Eversense system is the first long-term implantable CGM. A tiny sensor is implanted in the upper arm for 90 days, and a small transmitter is worn over the insertion site. The transmitter must be taken off and charged daily. The system is controlled by a smartphone app and requires daily finger sticks for calibration. Due to COVID-19, production of the device is on hold.
Cost and Insurance Coverage
Getting a prescription from a provider is the first step to using a CGM device, but Medicare has several criteria that must be met to qualify for CGM coverage.
- A patient must currently be testing their blood sugar with a blood glucose meter four or more times daily.
- A patient must also be treated with three or more daily injections of insulin or use a Medicare-covered insulin pump.
- A patient’s insulin doses must require frequent adjustments on the basis of blood sugar test results.
- A prescribing physician must have seen the patient for an in-person evaluation within six months of ordering a CGM device. And every six months following the initial prescription of the CGM device, the patient must have an in-person follow-up visit with their healthcare provider to assess adherence to the CGM regimen.
For the Freestyle Libre, there aren’t any commercial insurance coverage criteria to meet. Patients can obtain their prescribed Libre through a major retail pharmacy, and it will be covered for a branded copay. For the other systems, commercial insurances vary in their coverage requirements. It does appear, however, that the coverage requirements are similar to Medicare for the Dexcom G6, Medtronic Guardian Connect and Senseonics Eversense system.
Costs range widely and vary based on coverage. Patients can choose to pay out of pocket or contact their insurance carrier about coverage. Generally, there are separate costs for receivers (unless you use a smartphone), transmitters (except with the Freestyle Libre) and monthly sensors.
Medicare generally requires that patients obtain their CGM devices from durable medical equipment suppliers rather than a pharmacy. For patients with commercial insurance or no coverage, it’s best to get a device from a major retail pharmacy. There are several savings cards, such as GoodRx, WellRx and Singlecare, that can be obtained online, at a healthcare office or at some pharmacies.
Choosing the Right CGM for You
Choosing a CGM device is truly a decision based on one’s lifestyle and the features that are most important to them. Patients who wear an insulin pump and want it to communicate with the CGM will want a CGM that pairs with their pump. This is a decision that should be made based on research and consultation with a healthcare provider. Those working with an endocrinologist can discuss wearing a short-term professional CGM device to see if it is a helpful tool before committing to a personal CGM device.
Want more information? To attend Augusta Health’s monthly CGM informational workshop, “Continuous Glucose Monitor—Is It Right for Me?,” contact Kara McGill-Meeks at firstname.lastname@example.org or (540) 213-2539 to register. Depending on reopening guidelines, the workshop may be virtual, in person or both.