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February 14, 2024

Continuous Glucose Monitor (CGM) Supply Allowance

National DME MAC Education

The continuous glucose monitor (CGM) supply allowance codes A4238 and A4239 can be billed up to a maximum of three (3) units of service (UOS) per ninety (90) days at a time. Standard refill requirements do not apply to CGM supply fee codes A4238 or A4239. For example, if A4238 was billed on December 5, 2023, the next billable date for a 30-day supply would be January 4, 2024, and for a 90-day supply would be March 4, 2024. Noridian Healthcare Solutions and CGS Administrators, LLC have continuous glucose monitor supply allowance calculators located on their websites to help suppliers with determining accurate billing dates: CGM Supply Allowance Billing Calculator

Procedure code A4239 is the procedure code for all non-adjunctive CGM supplies and accessories. Non-adjunctive CGM supplies include, but are not limited to a CGM sensor, a CGM transmitter, a home blood glucose monitor, and related blood glucose monitor (BGM) supplies (such as test strips, lancets, lancing devices, and calibration solutions) and all batteries. Claims for supplies must be billed as 1 unit of service per 30 days. Effective January 1, 2024, up to 3 units of service are allowed when billing CGM supplies. If providing and billing for a 90-day supply, then 3 units of service would be submitted on the claim.

Adjunctive CGM devices do not replace a standard home BGM. The supply allowance for an adjunctive CGM (A4238) encompasses all items necessary for the use of the device and includes but is not limited to, the CGM sensors and transmitters. Code A4238 does not include a home BGM or related BGM testing supplies. The BGM supplies may be billed separately, in addition to code A4238 for the adjunctive CGMs. Refer to the Glucose Monitors LCD-related Policy Article (A52464)External Website for this guidance.

The CGM supply allowance does not follow standard documentation requirements for refills.  If a Medicare beneficiary requires additional items (e.g., sensors) during the billing period, the DME supplier must provide them at no charge to the beneficiary or to the Medicare program.  A4238 and A4239 are supply allowances and the DME supplier must provide the items the beneficiary requires/requests to use their continuous glucose monitor in their home.  Supply items must not be billed separately as any claims will be denied as unbundling.

If a DME supplier wants to provide CGM items prior to the expected end of the current supply, they are welcome to do so, but they must not bill the Medicare program until the 30 or 90 days has passed, depending on when the items were billed last. When a DME supplier provides either a 30-day or 90-day supply, a claim narrative indicating the number of supplies is not required. The presence of 1 unit of service will indicate a 30-day supply and 3 units of service will indicate a 90-day supply.

The date of service for procedure codes A4238 and A4239 should not be billed with a span date. The “From” and “To” date fields on the claim should be the same. Claims for procedure codes A4238 and A4239 billed with a span date will be returned as unprocessable. Unprocessable claims must be corrected and resubmitted; they do not have appeal rights or the ability to be reopened or adjusted.

Refer to the Glucose Monitors LCD (L33822)External Website and LCD-related Policy Article (A52464)External Website for additional information concerning the CGM supply allowance.


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