HCPCS Code A4239: Supply Allowance for Non-Adjunctive, Non-Implanted Continuous Glucose Monitor (CGM)

Learn about HCPCS Code A4239, the monthly supply allowance for non-adjunctive continuous glucose monitors, covering CGM sensors and related items.

Use Code

## **What is a non-adjunctive CGM supply allowance?** A non-adjunctive CGM supply allowance refers to the bundled coverage and payment for all necessary supplies used with certain continuous glucose monitors that can be used to make treatment decisions without the need for confirmatory fingerstick tests. Under HCPCS code A4239, the allowance applies to the monthly supply allowance associated with non-adjunctive CGM systems, which may include CGM sensors, transmitters, and other related items. Unlike adjunctive CGM systems, which require verification with home blood glucose monitors, non-adjunctive CGMs provide accurate enough readings for direct insulin dosing and ongoing diabetes management. The Centers for Medicare and Medicaid Services (CMS) and other payers define A4239 as covering supplies for adjunctive non-implanted continuous glucose monitoring systems. This makes it distinct from allowances tied to an implanted continuous glucose monitor, which follow separate billing rules. The CGM supply allowance under A4239 simplifies billing because providers and patients do not submit claims for each individual item; instead, the single monthly allowance covers all CGM supply needs. This is especially important since it includes everything required for the proper functioning of continuous glucose monitors, ensuring glucose monitors are fully supported in daily use. Some payers also provide guidance on correct coding and how the supply allowance interacts with private coverage. For example, while Medicare defines this as A4239, private insurers may issue their own coding guidelines for claims processing. These rules ensure that continuous glucose monitors and the corresponding CGM supply allowance are billed appropriately, avoiding claim denials. In short, A4239 establishes a standardized supply allowance for patients using non-adjudicative continuous glucose monitor CGM systems. It reflects the recognition that CGM devices are central to diabetes care, reducing reliance on adjunctive non-implanted continuous monitoring or home blood glucose monitors, and providing a comprehensive monthly benefit for patients.

## **HCPCS code A4239 documentation requirements** To ensure proper billing and coverage, providers must include clear and detailed documentation when prescribing and supplying CGM items under HCPCS code A4239. - Documentation must state that the supplies are for a non-adjunctive continuous glucose monitor (CGM) covered under A4239. - Records should specify the quantity and type of CGM supplies provided (e.g., sensors, transmitters). - Clinical notes must confirm the medical necessity for ongoing CGM use in diabetes management. - The treating provider should indicate that the supplies are essential for the proper functioning of the prescribed CGM system. - Documentation should align with payer and Medicare requirements to support coverage and proper billing.

## **A4239 billing requirements** To ensure accurate claims and compliance, providers must follow specific billing requirements for HCPCS code A4239: - Confirm that the supplies billed are for an approved non-adjunctive continuous glucose monitor (CGM). - Bill A4239 provides a monthly supply allowance, which includes all necessary CGM sensors, transmitters, and related items. - Do not unbundle or bill individual CGM supply items separately, as they are included in the allowance. - Apply the correct HCPCS code and any payer-required modifiers to support proper claim processing. - Ensure billing aligns with Medicare and private payer policies, with documentation supporting ongoing medical necessity.

## **Other relevant codes** - **A4239** – Supply allowance for non-adjunctive, non-implanted continuous glucose monitor, per month - **E2103** – Non-adjunctive, non-implanted continuous glucose monitor, includes all supplies and accessories, per month - **A4238** – Supply allowance for implanted continuous glucose monitor, per month (includes sensors and all necessary supplies) - **E2102** – Implanted continuous glucose monitor, includes all supplies and accessories, per month

Frequently asked questions

Yes. The allowance covers CGM sensors and all required supplies necessary for the functioning of approved non-adjunctive CGM systems.

Supplies for devices within the Freestyle Libre portfolio fall under A4239. Providers should follow payer rules and apply the appropriate Libre portfolio billing codes to ensure correct claims processing.

In some cases, related BGM testing supplies may be used as a backup or when readings need confirmation, particularly if a patient has experience with older or adjunctive CGM devices. Documentation should note why they are needed and apply correct Freestyle Libre portfolio billing practices if relevant.