Continuous Glucose Monitor (CGM) Billing and Supply Allowance

CMS has issued an update on the Glucose Monitor – Policy Article effective as of January 1, 2024. A supplier now has the option to bill and dispense up to a 90-day supply for procedure codes A4238 (Adjunctive CGM) and A4239 (Non-Adjunctive CGM).

The policy article states:

“Up to a maximum of three (3) months, ninety (90) days of the supply allowance may be billed for code A4238 or A4239 to the DME MAC at a time and suppliers may not dispense more than a ninety (90) day supply.”

Below is a helpful chart to categorize the Dexcom and FreeStyle CGM products, their respective NCPDP billing units, and corresponding days’ supply.

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Product NDC NCPDP Billing Unit Day’s Supply
Dexcom G6 Receiver 08627-0091-11 1 Each Once a year
Dexcom G6 Transmitter 08627-0016-01 1 Each Every 3 months
Dexcom G6 Sensor 08627-0053-03 3 Each Every 30 days
Dexcom G7 Receiver 08627-0078-01 1 Each Once a year
Dexcom G7 Sensor 08627-0077-01 1 Each Every 10 days
FreeStyle Libre 14-day Sensor 57599-0001-01 1 Each Every 14 days
FreeStyle Libre 14-day Reader 57599-0002-00 1 Each Every 3 years
FreeStyle Libre Reader 57599-0000-21 1 Each Every 3 years

PAAS Tips:

  • When billing Medicare Part B claims for procedure codes A4238 or A4239, claims are billed as 1 unit of service (UOS) per 30 days
  • The NCPDP billing units shown in the chart above would apply to non-Medicare Part B claims
  • A CGM supply allowance includes all items necessary for the use of the device and includes, but is not limited to, CGM sensors and transmitters
    • For adjunctive CGMs , the supply allowance code (A4238), does not include supplies for a Blood Glucose Monitor (BGM.). Any required BGM supplies must be billed separately
    • For non-adjunctive CGMs, the supply allowance code (A4239), also includes a home BGM and related supplies in the bundled payment (test strips, lancets, lancing device, calibration solution, and batteries)
    • See our April 2022 Newsline, Billing Blood Glucose Test Strips for a Patient Who Utilizes a Continuous Glucose Monitor for the definitions of Adjunctive and Non-Adjunctive CGMs
  • The supplier must monitor usage and verify the beneficiary has sufficient supplies to last for each 30-day billing period
  • Utilize the CGM Supply Allowance Billing Calculator found on your DME MAC website to help determine when the next date of service can be billed
    • CGS
    • Noridian
  • Check the same/similar tool in myCGS for a complete claim history to be sure the patient has not received supplies from another supplier in the last 30 or 90 days
  • If the patient requires a replacement sensor, transmitter, or receiver due to a product failure, be sure to document and replace the item while reaching out to the manufacturer
  • Beware that any PBM, including Medicare B, will recoup or deny a claim if it is refilled too soon based on days’ supply guidelines above

Jennifer Ottman, CPhT
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