Continuous Glucose Monitors (CGMs)

CGMs typically provide a new glucose level every five minutes, meaning 288 times per day. CGM is like a video, providing a constant stream of information on glucose levels, trends, and overnight data. 

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CGMs are particularly useful after meals and overnight, as they can sound an alert when glucose levels drop or rise below a preset threshold. CGMs provide a good way to monitor time spent “in range” (time spent within a normal, pre-specified blood sugar range); for more on time-in-range goals.

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Some CGMs need to be calibrated with a fingerstick blood sugar reading for optimal sensor accuracy; two CGMs currently do not need fingerstick calibrations – Abbott's FreeStyle Libre (and Libre 2) and Dexcom’s G6.  

 

The eligibility criteria to get CGM covered by Medicare also remain the same:

• Uses a home blood glucose monitor (BGM) and performing four or more BGM tests per day

• On multiple daily injections of insulin or an insulin pump

• Insulin treatment regimen requires frequent adjustment on the basis of CGM

• In the six months prior to ordering the CGM, must have an in-person visit with the treating healthcare provider to determine the above criteria are met

• Every six months following the prescription of the CGM, must have in-person visits with the treating healthcare provider to assess diabetes treatment

 

The eligibility criteria to get CGM covered by Commercial Carriers: (BCBS, Aetna, Cigna, Humana, UHC etc.)

CGM is usually considered “durable medical equipment” and is subject to the same deductibles and copays as other types of DME.  Every CGM company has a team of specialists dedicated to helping you obtain maximum coverage.  Do your best to comply with their requests and supply them with the information they need to support your case.

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People with Type-1 (insulin-dependent) diabetes often qualify for insurance coverage, particularly if the following criteria are met:

• A history of hypoglycemia, documented in the physician’s chart/records

• Presence of hypoglycemia unawareness (lack of symptoms during the early phases of hypoglycemia)

• Erratic blood glucose levels

• Suboptimal HbA1c

• Frequent blood glucose monitoring

• Having completed diabetes self-management education

 

In some cases, people with Type-2 diabetes, whether or not insulin is used, can obtain coverage if many of these same conditions exist.

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Most plans require the CGM to be prescribed by an endocrinologist.  Letters from both you and your physician, supporting your need for CGM, are often helpful.  And persistence pays!  If you are denied for coverage the first time around, go through the appeal process.  Many people who were initially denied are approved for coverage after the second, third, and even fourth round of appeals.

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Whenever possible, request an “external” appeal.  This requires your health insurer to pay a physician who is not employed by their company to review your case in detail.  An external appeal will usually cause the health insurance company to overturn their decision and begin covering your CGM.

 

What Supplies Do I Need?

CGMs require three basic parts:

 

Sensor – monitors real-time glucose levels, usually every five minutes. The sensor is inserted under the skin by the user with a simple applicator. Sensors are normally worn for 7-14 days, depending on the system. However, the new Eversense Implantable CGM system (which includes a sensor inserted under the skin of the upper arm) can be worn for up to 90 days.

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Transmitter – sits on top of the sensor and sends glucose information to a receiver or a smartphone app. Most systems have a transmitter that is reusable for 3-12 months. In the case of FreeStyle Libre, there is no reusable transmitter; each sensor is fully disposed after 14 days and a new one is put on.

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Smartphone app or receiver – displays real-time glucose level, whether blood glucose is trending up or down, and glucose history. Most CGMs offer smartphone apps for viewing data. Abbott and Dexcom also offer handheld devices for people that don’t use a smartphone. Some CGM devices also send the glucose value to an insulin pump, including a growing number that can automatically deliver insulin accordingly.

 

What CGMs are available in the US?

Currently, four companies have personal CGM devices on the US market: Abbott (FreeStyle Libre and Freestyle Libre 2), Dexcom (the G4 and G5, which were discontinued in June 2020, and the G6), Medtronic (Guardian Connect and Guardian Sensor 3), and Senseonics Eversense. The table below compares some of their key features. Pricing varies with insurance coverage and can be provided by the company. For people paying out-of-pocket (with no insurance coverage), FreeStyle Libre is the least expensive CGM as of this writing.