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Certificate of Medical Necessity

Also known as: CMN, CMS-484, CMS-846

A form completed by your physician certifying that a piece of DME is medically necessary for Medicare billing.

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A Certificate of Medical Necessity is a standardized CMS form that a treating physician must complete to document why a specific piece of durable medical equipment is medically necessary for a patient. Different CMN forms apply to different equipment categories.

For insulin pumps, the CMS-484 (Insulin Used with External Infusion Pumps) is required. For therapeutic shoes, there is a separate prescribing physician statement form. For CGM, written documentation of medical necessity (including C-peptide level for pumps) must be on file at the DME supplier.

The CMN (or equivalent documentation) must be completed, signed, and dated by the treating physician — not the DME supplier. The supplier cannot write the physician's responses. Inaccurate or fraudulent CMNs are a federal crime.

A good DME supplier will send the physician the correct forms, pre-populate the patient demographic information, and follow up to obtain signatures — minimizing burden on the physician's office.

Related diabetic supply categories

Insulin Pumps Supplies Cgm Supplies Diabetic Shoes Supplies

Related terms

  • DME — Medical equipment designed for repeated use that serves a medical purpose — the Medicare category covering diabetic supplies.
  • Prior Authorization — Insurer approval required before certain expensive supplies or medications are covered.
  • Insulin Pump — A programmable device that delivers a continuous basal dose of insulin plus user-triggered bolus doses.
  • Medicare Part B — The Medicare component that covers outpatient medical services and durable medical equipment — the pathway for most diabetic supply coverage.

Frequently asked

What is Certificate of Medical Necessity?

A form completed by your physician certifying that a piece of DME is medically necessary for Medicare billing. A Certificate of Medical Necessity is a standardized CMS form that a treating physician must complete to document why a specific piece of durable medical equipment is medically necessary for a patient. Different CMN forms apply to different equipment categories.

How does Certificate of Medical Necessity relate to Medicare coverage?

Medicare Part B covers most durable medical equipment related to Certificate of Medical Necessity. Contact us to verify your specific coverage for related diabetic supplies.

Where can I get diabetic supplies related to Certificate of Medical Necessity in Phoenix?

We deliver Medicare-covered diabetic supplies throughout the Phoenix metro area. Call us or complete the form above to verify your coverage.

Questions about Medicare coverage for diabetic supplies? We answer the phone in under 60 seconds.

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