FY2025 ICD-10 updates: what changed
⚡ Effective October 1, 2024 (FY2025)
The FY2025 update introduced new subcategory E66.81x — obesity classified by class rather than by caloric etiology. This is the most significant change to obesity coding in years and has direct implications for how you document and bill.
| Code | Description | BMI range | Status |
|---|---|---|---|
| E66.811 | Obesity, Class 1 | 30.0–34.9 | New FY2025 |
| E66.812 | Obesity, Class 2 | 35.0–39.9 | New FY2025 |
| E66.813 | Obesity, Class 3 | ≥40.0 | New FY2025 |
| E66.01 | Morbid (severe) obesity due to excess calories | ≥40.0 (or BMI ≥35 + serious comorbidity) | Use with caution |
| E66.09 | Other obesity due to excess calories | 30.0–39.9 | Still valid |
Critical nuance — E66.813 vs E66.01: When a provider documents "Class 3 obesity," assign E66.813. When "morbid obesity" or "severe obesity" is documented without class specificity, assign E66.01. If both are documented together, use only E66.813 (more specific, per April 2025 Official Coding Guideline update). Do not report both simultaneously. This distinction also affects HCC risk adjustment: E66.811 and E66.812 do not risk-adjust under current payment models; E66.01 and E66.813 do.
E66 obesity codes — complete reference
| Code | Description | Notes |
|---|---|---|
| E66.01 | Morbid (severe) obesity due to excess calories | BMI ≥40, or BMI ≥35 with serious comorbidity. Requires documentation of "morbid" or "severe." Still the primary PA code for many insurers — do not abandon it. |
| E66.09 | Other obesity due to excess calories | BMI 30–39.9. Less specific than new class codes — prefer E66.811/812 when class is documented. |
| E66.1 | Drug-induced obesity | Use when obesity is a medication side effect (e.g., antipsychotics, corticosteroids). Requires adverse effect coding — also report T codes for the causative drug. |
| E66.2 | Morbid obesity with alveolar hypoventilation | Obesity hypoventilation syndrome (OHS / Pickwickian syndrome). Separate from OSA. |
| E66.3 | Overweight | BMI 25.0–29.9. Not a qualifying code for GLP-1 PA on its own — must pair with qualifying comorbidity for BMI 27–29.9 indication. |
| E66.811 | Obesity, Class 1 | FY2025 BMI 30–34.9. Use when "Class 1" is documented. |
| E66.812 | Obesity, Class 2 | FY2025 BMI 35–39.9. Use when "Class 2" is documented. |
| E66.813 | Obesity, Class 3 | FY2025 BMI ≥40. Use when "Class 3" is documented. Preferred over E66.01 when class is specified. |
| E66.9 | Obesity, unspecified | Avoid — lowest specificity, weakest PA support, highest audit risk. Use only when no other code applies. |
Primary vs secondary diagnosis: Code obesity as a primary diagnosis when it is the reason for the visit (obesity management visit, GLP-1 prescribing visit). Code it as a secondary diagnosis when treating another condition in a patient who has obesity. For GLP-1 PA submissions, obesity must appear as a listed diagnosis — its position on the claim is less critical than its presence and specificity.
Z68 BMI codes
Z68 codes are supplemental — they document the specific BMI value and must always be paired with an E66 code, never used alone. Include a Z68 code on every claim where BMI is documented in the chart.
| Code | BMI range (adult) | PA relevance |
|---|---|---|
| Z68.27–Z68.29 | 27.0–29.9 | Overweight with comorbidity — supports Wegovy/Zepbound BMI ≥27 indication |
| Z68.30–Z68.34 | 30.0–34.9 | Class 1 obesity — pair with E66.811 or E66.09 |
| Z68.35–Z68.39 | 35.0–39.9 | Class 2 obesity — pair with E66.812 or E66.01 (with comorbidity) |
| Z68.41 | 40.0–44.9 | Class 3 / morbid — pair with E66.813 or E66.01 |
| Z68.42 | 45.0–49.9 | Class 3 — pair with E66.813 or E66.01 |
| Z68.43 | 50.0–59.9 | Class 3 — pair with E66.813 or E66.01 |
| Z68.44 | 60.0–69.9 | Class 3 — pair with E66.813 or E66.01 |
| Z68.45 | ≥70.0 | Class 3 — pair with E66.813 or E66.01 |
Z68 codes are not standalone billable diagnoses. Submitting a Z68 code without a corresponding E66 code is a common denial trigger. The Z68 provides specificity; the E66 provides the diagnosis. Both are required on every obesity claim where BMI is documented.
How to pair E66 + Z68 — clinical examples
Code pairing quick reference
E66.811 + Z68.30–34 Class 1 obesity, BMI 30–34.9
E66.812 + Z68.35–39 Class 2 obesity, BMI 35–39.9
E66.813 + Z68.41–45 Class 3 obesity, BMI ≥40 (documented as "Class 3")
E66.01 + Z68.41–45 Morbid obesity, BMI ≥40 (documented as "morbid" or "severe" without class)
E66.01 + Z68.35–39 Morbid obesity, BMI 35–39.9 with serious comorbidity (document the comorbidity)
E66.3 + Z68.27–29 + [comorbidity] Overweight + comorbidity — BMI 27–29.9 GLP-1 indication
Comorbidity codes for GLP-1 prior authorization
For patients with BMI 27–29.9, at least one weight-related comorbidity is required to qualify for GLP-1 coverage. For patients with BMI ≥30, comorbidities strengthen the PA and can be the difference between approval and denial. Always code every active comorbidity documented in the visit note.
| Code | Condition | Notes |
|---|---|---|
| I10 | Essential (primary) hypertension | Most common qualifier. Ensure BP is documented in the visit note. |
| E11.9 | Type 2 diabetes mellitus, without complications | Strong PA qualifier. Use E11.x codes with complication specificity when applicable. |
| E11.65 | T2DM with hyperglycemia | More specific than E11.9 when elevated glucose is documented. |
| E78.5 | Hyperlipidemia, unspecified | Common qualifier. Use E78.00 or E78.1 for greater specificity. |
| E78.00 | Pure hypercholesterolemia, unspecified | Preferred over E78.5 when LDL elevation is the documented finding. |
| G47.33 | Obstructive sleep apnea (adult) | Required for Zepbound OSA indication. See OSA section below. |
| I25.10 | Atherosclerotic heart disease of native coronary artery without angina pectoris | Key code for Wegovy cardiovascular indication (SELECT trial). See CV section. |
| I63.x | Cerebral infarction | History of stroke — supports Wegovy CV indication. |
| I73.9 | Peripheral vascular disease, unspecified | PAD — supports Wegovy CV indication. |
| K76.0 | Fatty liver, not elsewhere classified (MASLD/NAFLD) | Increasingly recognized comorbidity. Document in chart if present. |
| E11.51 | T2DM with diabetic peripheral angiopathy without gangrene | Supports CV risk classification. |
| Z82.49 | Family history of ischemic heart disease and other diseases of the circulatory system | Secondary supporting code for CV risk. |
OSA + Zepbound: the sleep apnea pathway
Zepbound (tirzepatide) received FDA approval in June 2024 for moderate-to-severe obstructive sleep apnea in adults with obesity — the first pharmacotherapy approved for this indication. This opens a distinct PA pathway for patients who may not qualify under the obesity-only criteria.
Zepbound OSA indication — required code combination
G47.33 + E66.01 / E66.812 / E66.813 + Z68.3x–45 OSA + obesity (any class) + BMI
- Document the AHI — moderate-to-severe OSA requires AHI ≥15 events/hour. The diagnosis alone is not sufficient; severity must be in the chart.
- Use G47.33 (adult OSA), not G47.30 (unspecified sleep apnea) or G47.31 (primary central sleep apnea).
- Document the source of the OSA diagnosis — sleep study report, pulmonology note, or prior PAP therapy records should be referenced or attached.
- Include prior treatment history for OSA (PAP therapy compliance or intolerance) if submitting for OSA-indication PA rather than obesity-indication PA.
- Patients who qualify under the OSA pathway but were denied for obesity-only indication may have better success re-submitting under the OSA indication with G47.33 as the primary code.
Cardiovascular indication: Wegovy and the SELECT trial
In March 2024, FDA approved an expanded indication for Wegovy (semaglutide 2.4 mg) for reduction of cardiovascular death, non-fatal MI, and non-fatal stroke in adults with established cardiovascular disease and BMI ≥27. This is a separate PA pathway from the weight-management indication.
Wegovy CV indication — code combination
I25.10 + E66.3 / E66.811+ + Z68.27+ Established CVD + overweight/obesity + BMI ≥27
| Code | CVD condition | Notes |
|---|---|---|
| I25.10 | Atherosclerotic heart disease, no angina | Primary code for established ASCVD without current angina. |
| I25.110 | Atherosclerotic heart disease with unstable angina | Use when angina is documented. |
| I63.x | Cerebral infarction (stroke) | History of stroke qualifies under SELECT criteria. |
| I73.9 | Peripheral vascular disease, unspecified | PAD qualifies as established CVD for the SELECT indication. |
| Z86.73 | Personal history of transient ischemic attack (TIA) | Supporting code — may strengthen CV risk documentation. |
CV pathway vs weight pathway: Some payers cover Wegovy under the CV indication but not the weight-management indication (or vice versa). If a patient with established CVD was denied for obesity-only PA, consider resubmitting under the cardiovascular indication using I25.10 or equivalent as the primary diagnosis. Document the cardiovascular risk reduction rationale explicitly in your letter of medical necessity.
Coding for continuation of therapy
Continuation PAs are a distinct submission from initial PAs and require different framing. The most common mistake is submitting a continuation as if it were a new request — this invites denial based on changing BMI.
- Check "continuation of therapy" or "renewal" — never "new request" on renewals. This affects the clinical criteria applied by the reviewer.
- Add Z79.899 (long-term use of other medication) to the code set for continuation visits. This signals ongoing therapy, not initiation.
- If the patient's BMI has decreased because the medication is working, document that the weight loss is attributable to the medication — do not let a BMI drop automatically disqualify a continuation PA.
- Document comorbidity improvement (e.g., blood pressure reduction, HbA1c improvement) as evidence of clinical response, not as evidence the medication is no longer needed.
- When switching from Wegovy to Zepbound (or vice versa), explicitly document the reason for the switch (inadequate response, side effects, formulary change) — payers may require justification for brand switches.
- If a patient is switching GLP-1 medications, treat it as a new PA for the new medication with the switch reason documented, not as a simple continuation.
| Code | Use case |
|---|---|
| Z79.899 | Long-term (current) use of other medication — add to continuation of therapy visits for GLP-1 medications |
| Z71.3 | Dietary counseling and surveillance — document if nutrition counseling is part of the visit (strengthens PA) |
| Z71.82 | Exercise counseling — document if exercise counseling is provided |
| Z68.x | Current BMI — always update Z68 code at every visit, even if BMI has decreased from prior visit |
How coding directly affects prior authorization outcomes
✓ Coding that strengthens PA
- Specific E66 class code (E66.812, E66.813) rather than E66.9
- Z68 BMI code paired on every claim
- All active comorbidities coded — not just the chief complaint
- G47.33 with documented AHI ≥15 for Zepbound OSA pathway
- I25.10 + BMI ≥27 for Wegovy CV indication
- Z79.899 on continuation submissions
- Z71.3 / Z71.82 showing lifestyle intervention is ongoing
✗ Coding that triggers denials
- E66.9 (unspecified) as the primary obesity code
- Z68 code submitted without E66 code
- Missing comorbidity codes that are documented in the chart
- Continuation submitted as "new request"
- BMI decrease coded without documentation that weight loss is medication-attributed
- G47.30 instead of G47.33 for OSA
- Prediabetes coded as T2DM (E11.x) — inaccurate and an audit risk
Common coding errors — and how to avoid them
| Error | Why it happens | Correct approach |
|---|---|---|
| Using E66.9 by default | EHR defaults or quick picks often populate unspecified codes | Use E66.811–813 when class is documented; E66.01 when "morbid/severe" is documented; E66.09 when neither is specified but etiology is excess calories |
| Submitting Z68 without E66 | BMI is auto-captured by nursing but not linked to an E66 code by the provider | Always confirm E66 is on the claim whenever a Z68 is captured. Z68 alone is a non-billable supplemental code. |
| Coding E66.01 + E66.813 together | EHR allows both; staff may code both when "Class 3 morbid obesity" is documented | Per April 2025 guideline update: when both are documented, use only E66.813. It is the more specific code. |
| Using G47.30 instead of G47.33 for OSA | G47.30 is "sleep apnea, unspecified" — a common EHR default | Use G47.33 specifically for adult OSA. Zepbound OSA PA criteria reference G47.33 explicitly. |
| Omitting comorbidities present in the chart | Providers focus on the obesity visit, not on capturing all active diagnoses | At each GLP-1 prescribing visit, actively review and code all documented comorbidities — HTN, dyslipidemia, T2DM, MASLD, OSA. Each strengthens PA. |
| Coding prediabetes as E11.x (T2DM) | Clinicians sometimes use T2DM codes for prediabetes in hopes of improving PA odds | Use R73.09 (other abnormal glucose) or E11.x only when T2DM is actually diagnosed. Upcoding is an audit and compliance risk. |
| Not updating Z68 on follow-up visits | Z68 is seen as administrative and skipped on follow-ups | Update Z68 at every visit. An improving BMI with continuation of therapy should be accompanied by documentation explaining why the medication is still clinically indicated. |
Documentation tips for cleaner coding and stronger PAs
- Specify obesity class in your documentation. Write "Class 2 obesity" or "Class 3 obesity" — not just "obese" or "morbidly obese." Class-specific language maps directly to the new E66.81x codes and produces more defensible coding.
- Document BMI with a date at every visit. Insurance reviewers check that BMI documentation is current. A BMI from six months ago on a current claim is a denial trigger.
- Link comorbidities to obesity explicitly. "Hypertension in the setting of Class 2 obesity" is stronger documentation than listing them separately. This supports medical necessity and comorbidity-dependent PA pathways.
- Document prior treatment history at every initial PA. Insurers require evidence of failed lifestyle intervention. Note duration, modality, and outcome ("Patient engaged in structured dietary counseling for 6 months with 2% weight loss").
- For OSA + Zepbound: Include the AHI value, sleep study date, and current PAP therapy status. Moderate-to-severe OSA (AHI ≥15) must be explicit — document it as such, not just "OSA."
- For continuation PAs: Document weight loss achieved, comorbidity response (BP improvement, HbA1c trend), and clinical rationale for ongoing therapy. Frame it as: medication is working, stopping it would reverse gains.
- Audit your EHR defaults. Many EHR quick-picks default to E66.9 or G47.30. Update your favorites/preference lists to include the correct specific codes — this single step eliminates the most common errors across your entire panel.
- When a PA is denied: Request a peer-to-peer call before writing a written appeal — phone appeals outperform written appeals. When writing, reference both the ICD-10 codes and the specific FDA indication language that applies to your patient.
Related provider guide
Prior Authorization for GLP-1 Medications: Step-by-Step
PA workflows, denial reasons, appeal strategies, and a letter of medical necessity template.
→
Provider resource disclaimer: This reference is for educational purposes and reflects ICD-10-CM codes as of FY2026 (effective October 1, 2025). Coding guidelines are updated annually — always verify against the current official ICD-10-CM edition and your institution's compliance standards. This content does not constitute medical advice, legal advice, billing guidance, or compliance advice. InformedPlate is an educational resource, not a substitute for professional medical, legal, or coding judgment.