# The Documentation Gap

## Why Continuous Glucose Monitoring (CGM) Claim Performance Is Decided Before Claims Submission

_Published by STTIL Solutions_
_A reference for CGM suppliers, Revenue Cycle Management teams, and other billing professionals_

---

## The Core Problem

Clean claim performance in CGM is not primarily a billing problem. It is a documentation problem, and the gap opens upstream, not at claims submission.

Centers for Medicare & Medicaid Services (CMS) compliance reporting is clear: 67.6% of improper payments for glucose monitoring supplies during the 2024 reporting period were attributed to missing documentation. Not insufficient. Absent. The documentation records were unable to be created, collected, or verified before the CGM claim was filed.

By the time a denial, write-off, or audit flag appears in your billing queue, capital exposure is already at risk. The window to address it closed before the supplies left the building.

This paper maps five checkpoints in the CGM documentation chain where that window is open, what tends to go wrong at each one, and why resupply is where the most preventable risk lives.

---

## The Resupply Context

The majority of CGM claim volume is not first-time dispensing. It's at resupply. And resupply introduces a documentation dynamic that first-time workflows often miss: the documentation is never static.

Provider Enrollment, Chain, and Ownership System (PECOS) enrollment changes. Prior authorizations expire. The qualifying visit requirement creates a recurring window that runs on the patient's care calendar, not the billing calendar. SWO currency must be confirmed against the order being fulfilled now, not the file from the original onboarding.

For resupply, documentation review is not a one-time event. It is a recurring checkpoint for every shipment. Each resupply cycle carries its own exposure, and that exposure is determined before any CGM supplies goes out the door.

---

## The Five Checkpoints

The CGM documentation chain minimally has five distinct points where gaps form. Each one precedes billing and likely outside the control of the supplier. Each one shapes the outcome of a claim that has yet to be filed.

### 1. The Qualifying Visit

Coverage eligibility for CGM rests on clinical documentation from a qualifying physician encounter. The treating physician's notes must reflect the coverage criteria: insulin treatment type, frequency of adjustment, and medical necessity. Not inferred from the order. In the chart.

For resupply, the qualifying visit anchors the entire downstream timeline. If the encounter is not documented before the resupply window opens, the chain is already misaligned before a single order is processed.

### 2. The Standard Written Order

The SWO must be current, complete, and field-matched to the claim before supplies ship. A prescriber change not reflected in the SWO, an outdated quantity, or a mismatch between the order and the claim creates an exception the claim cannot survive on its own.

For resupply, this means confirming the SWO against the specific order being fulfilled now, not the record on file from the original dispensing.

### 3. PECOS Enrollment

The prescriber on record must have active PECOS enrollment at the time supplies ship, not when they were added to your system. Physicians move practices, change enrollment categories, or allow enrollment to lapse.

Supplies shipped against an order from a prescriber with a lapsed enrollment carry that exposure from the moment they go out the door. It is one of the most common and most preventable sources of capital risk in the resupply documentation chain.

### 4. Prior Authorization Currency

PA must be active and aligned with the specific HCPCS codes on the current shipment. Not just present; aligned. Authorization windows expire, and code list requirements can shift mid-coverage-period without direct notice to the supplier.

For resupply, confirming PA currency before anything ships is the only point in the workflow where this exposure can be addressed without financial consequence.

### 5. Proof of Delivery (POD)

POD documentation must be complete and consistent with the claim before the claim is filed. For mail-order and ship-and-service delivery, the shipment invoice and carrier tracking record must be linked. For in-person, the signed delivery slip must match the claim on description, quantity, and date.

One mismatch is enough to change the outcome on an otherwise clean claim. By the time it surfaces as a denial, the product has long since left the building.

---

## What the Data Shows

CMS compliance reporting on glucose monitoring supplies is unambiguous:

67.6% of improper payments during the 2024 reporting period were attributed to absent documentation. Records that were not available, collected, or in place at the time of audit.

Documentation-related causes consistently account for the majority of DMEPOS improper payments across audit cycles, outpacing billing errors and coverage determinations as the primary driver.

These are not billing errors caught after the fact. They are upstream documentation gaps. Documentation that was not generated or verified before the supplies were delivered or a claim was filed.

---

## What This Means Operationally

The teams with the strongest clean claim rates are not faster at denial management. They have upstream documentation visibility.

For resupply workflows specifically, that means the ability to confirm, per patient, per shipment:

- Whether the qualifying visit is documented before the resupply window opens
- Whether the SWO is current and field-matched to this order, not the original file
- Whether PECOS enrollment is active for the prescriber on record right now
- Whether the PA on file covers the codes on this specific shipment
- Whether POD documentation will be complete and linked before the claim is filed

Most RCM platforms surface claim status at the payer response stage. The denial work queue is a lagging indicator. The exposure it reflects was created before the resupply was ever initiated.

The question is whether your documentation chain is visible before anything ships, or only after the remittance comes back.

---

## A Note on Payer Variation

The SWO framework governs Medicare DMEPOS, but suppliers working across Medicare, Medicaid, and commercial payers face variation in documentation requirements. That variation is not always communicated when requirements change.

| Requirement         | Medicare DMEPOS                       | Medicaid                       | Commercial Payers                |
| ------------------- | ------------------------------------- | ------------------------------ | -------------------------------- |
| Order standard      | SWO (eff. Jan 1, 2020)                | Varies by state                | Varies; some still reference CMN |
| Face-to-face        | Required for designated items         | Varies                         | Varies                           |
| PECOS enrollment    | Required                              | Provider enrollment equivalent | Credentialing varies             |
| Prior authorization | Required for PA-designated codes      | Varies                         | Varies by plan and product       |
| Proof of delivery   | Required; specific field requirements | Required; varies               | Required; varies                 |

A current, payer-specific documentation matrix is a working operational tool, not a one-time setup.

---

_The documentation gap is real, measurable, and addressable before the supplies ever leave the building._

_STTIL Solutions builds tools for CGM suppliers and care teams that surface documentation status upstream. Learn more at sttilsolutions.com_

_CMS data references: CMS Glucose Monitoring Supplies compliance tip (updated February 2026); CMS Standard Documentation Requirements (Article ID 55426); CGS Medicare Final Rule CMS-1713-F SWO FAQ; LCD L33822 Glucose Monitors._
