CGMCoverage & appeals · continuous glucose monitoring

CGM denial: how to appeal a continuous glucose monitor denial

Medicare loosened its CGM rules in April 2023, and that's exactly why so many denials are now winnable: most rest on a criterion the chart can satisfy, not on a service the plan refuses to cover.

Medicare expanded continuous glucose monitor coverage on April 16, 2023 under the Glucose Monitors local coverage determination (LCD L33822). A beneficiary with diabetes now qualifies if they are treated with insulin or have a documented history of problematic hypoglycemia — insulin is no longer required, and the old fingerstick-testing requirement was dropped. Ongoing coverage hinges on a follow-up visit at least every six months. Most denials trace to one of those facts being absent from the record rather than to a true coverage exclusion, which is what makes them appealable. Commercial plans set their own prior-authorization criteria, so the denial reason there is usually documentation or a preferred-device step rather than the Medicare rule.

How CGM is covered

Under Medicare's 2023 criteria, a CGM is covered for a patient with diabetes who is either treated with insulin or has a documented history of problematic hypoglycemia — for example, recurrent level 2 hypoglycemic events with glucose below 54 mg/dL, or a severe event. The update removed the prior requirement to document a minimum number of daily fingerstick checks and set no minimum frequency of insulin administration. Continued coverage requires a face-to-face visit — in person or by Medicare-approved telehealth — at least every six months to confirm the patient is using the device and following the treatment plan. Commercial plans cover CGM on their own medical-policy criteria, which vary by insurer and often run through prior authorization and a contracted durable-medical-equipment supplier.

Why CGM claims get denied

  • Medicare: the record didn't show insulin treatment or a documented history of problematic hypoglycemia — the two qualifying paths under the 2023 criteria.
  • Medicare: the every-six-months follow-up visit wasn't documented, so ongoing coverage lapsed.
  • The device or supplies were billed through a non-contracted DME supplier, or a coding/billing error.
  • Commercial: the plan's own prior-authorization criteria weren't met or weren't documented.
  • Commercial: a preferred-device or step requirement, or quantity limits on sensors and supplies.

Is a CGM denial worth appealing?

Often worth appealing

Usually worth appealing, because the common denial reasons are about the record, not the benefit. For Medicare, the appeal succeeds when the chart shows insulin treatment or a documented history of problematic hypoglycemia, plus the six-month visit for ongoing coverage. For commercial plans, map the documentation to the plan's specific CGM policy. The narrow exception is a plan that genuinely doesn't include CGM as a covered benefit — there the path is a formulary or benefit exception, not a medical-necessity appeal.

How to appeal a CGM denial

  1. 1

    Pin the exact criterion the denial cites

    Separate a Medicare LCD denial from a commercial prior-auth denial — they apply different criteria, and the appeal has to answer the one actually used.

  2. 2

    Document the qualifying path

    For Medicare, show insulin treatment or the problematic-hypoglycemia history (e.g., the recurrent low-glucose events), and attach the every-six-months visit note that keeps coverage active.

  3. 3

    For commercial plans, map the chart to the policy

    Tie the diabetes management history and clinical rationale to each element the insurer's own CGM coverage policy requires.

  4. 4

    Escalate on the right ladder

    A Medicare Advantage CGM denial follows the MA appeal process; a commercial denial goes through the internal appeal and then independent external review.

CGM — frequently asked

Does Medicare cover a CGM for type 2 diabetes if I don't use insulin?
Yes, since April 16, 2023. A patient with diabetes who isn't on insulin can qualify with a documented history of problematic hypoglycemia. Insulin treatment is no longer required, and the fingerstick-testing requirement was removed.
My CGM was denied even though I have diabetes — why?
Diabetes by itself isn't the Medicare criterion. The record has to show insulin treatment or a documented history of problematic hypoglycemia, and ongoing coverage needs a follow-up visit at least every six months. A denial usually means one of those was missing from the documentation.
Do I still need to log fingerstick glucose checks?
Not for the Medicare criteria — the 2023 update removed the fingerstick-testing requirement. A commercial plan can still ask for its own documentation, so check the policy the denial cites.

Related guides

CO-50 · medical necessityCO-197 · prior auth absentMedicare Advantage appeal

Sources

FDA-approved indications and payer prior-authorization criteria are paraphrased for plain-language reference, not reproduced verbatim, and vary by plan. This is general information, not medical, legal, or coverage advice — confirm against the current FDA label, the plan's policy, and the patient's benefit documents.

When the appeal has to be written, and cited

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