TL;DR: The Centers for Medicare & Medicaid Services modified NCD 100 governing glycated hemoglobin and glycated protein testing, effective March 7, 2026. Here's what changes for billing teams.
This CMS glycated hemoglobin coverage policy update under NCD 100 in the Medicare system clarifies medical necessity criteria, testing frequency limits, and documentation requirements for A1c and fructosamine tests billed to Medicare. The policy does not list specific CPT or HCPCS codes in the published data — more on that below. If your practice manages diabetic patients and bills Medicare for lab work, this update affects your reimbursement and your claim denial exposure starting now.
Quick-Reference Table
| Field | Detail |
|---|---|
| Payer | CMS (Centers for Medicare & Medicaid Services) |
| Policy | Glycated Hemoglobin/Glycated Protein — NCD 100 |
| Policy Code | NCD 100 |
| Change Type | Modified |
| Effective Date | March 7, 2026 |
| Impact Level | Medium — high volume test with frequency-based denial risk |
| Specialties Affected | Endocrinology, primary care, internal medicine, obstetrics (diabetic patients), clinical laboratories |
| Key Action | Audit your frequency of A1c and fructosamine billing per patient to confirm it aligns with NCD 100 criteria before submitting claims |
CMS Glycated Hemoglobin Coverage Criteria and Medical Necessity Requirements 2026
The core of this coverage policy is frequency. CMS draws a clear line between what's medically necessary and what will trigger a claim denial.
For a controlled diabetic patient, CMS considers glycated hemoglobin testing medically necessary no more than once every three months. That's four tests per year, maximum, under standard conditions. Bill a fifth test in a calendar year without documentation of clinical justification, and you're looking at a denial.
There are two exceptions that allow more frequent testing. First, if a patient's diabetes regimen has been changed to improve control, testing every one to two months is appropriate. Second, if an intercurrent event has disrupted previously stable control — major surgery or glucocorticoid therapy are the specific examples in the policy — more frequent testing is justified. Both situations require solid medical necessity documentation in the record before you bill.
Pregnant diabetic women get a different rule entirely. Glycated protein (fructosamine) testing is reasonable and necessary monthly for this population. That's because glycated protein measures glycemic control over a shorter window — one to two weeks — making it more clinically relevant during pregnancy than the standard A1c, which reflects a four-to-eight-week average.
For uncontrolled type 1 or type 2 diabetes, testing more than four times per year may be appropriate. But CMS is explicit: the clinical basis must be documented, and medical necessity documentation must support testing above the standard guideline. "Uncontrolled" is not a self-certifying diagnosis. Your documentation needs to back it up.
This is not new territory for CMS, but the March 7, 2026 effective date signals that MAC-level auditors may use this updated NCD 100 as a basis for reviewing claims. If your volume of glycated hemoglobin billing is high, treat this as a flag.
Prior authorization is not explicitly required under this NCD. However, don't let that lower your guard. Frequency limits without prior auth requirements mean post-payment audits and recoupment are the enforcement mechanism. Your exposure is retrospective, not prospective.
CMS Glycated Hemoglobin Exclusions and Non-Covered Indications
CMS is direct about what doesn't meet medical necessity under this coverage policy.
Glycated hemoglobin tests performed more frequently than every three months on a controlled diabetic patient are not considered reasonable and necessary. That's the ceiling for routine monitoring. If your billing team is running quarterly and the chart shows a stable A1c trajectory, you're at the limit. One more test without documented justification is a denial waiting to happen.
Testing more than once per month for pregnant diabetic women is also not covered. The monthly limit for glycated protein in this population is firm.
There's also an interference issue worth knowing. Many glycated hemoglobin assay methods produce unreliable results in patients with elevated fetal hemoglobin or variant hemoglobin molecules — think hemoglobinopathies like sickle cell disease or thalassemia. In these cases, the lab may flag the result as potentially unreliable. The appropriate alternative is glycated protein testing. Continuing to bill for glycated hemoglobin in patients with known hemoglobinopathies, when the assay is documented to have analytical interference, creates both a medical necessity problem and a clinical accuracy problem.
Abnormal erythrocyte conditions — hemolytic anemia included — are also listed as situations where glycated protein is the more appropriate test. If your ordering providers are still defaulting to A1c for these patients, that's a documentation and coding risk worth addressing with your medical director.
Coverage Indications at a Glance
| Indication | Status | Relevant Codes | Notes |
|---|---|---|---|
| Glycated hemoglobin testing for controlled diabetic patients | Covered | Not specified in policy data | Maximum every 3 months; more frequent = not covered without documentation |
| Glycated hemoglobin testing for altered or uncontrolled diabetes regimen | Covered | Not specified in policy data | Every 1–2 months acceptable; medical necessity documentation required |
| Glycated hemoglobin testing post-major surgery or glucocorticoid therapy | Covered | Not specified in policy data | Intercurrent event must be documented in the record |
| Glycated protein (fructosamine) testing for pregnant diabetic women | Covered | Not specified in policy data | Monthly limit; more frequent = not covered |
| Glycated protein testing for patients with hemoglobinopathies or hemolytic anemia | Covered | Not specified in policy data | Preferred over A1c when hemoglobin interference documented |
| Glycated hemoglobin to assess hypoglycemia in nesidioblastosis or insulinoma | Covered | Not specified in policy data | Below-normal result helps establish hypoglycemic state |
| Glycated hemoglobin more than 4x/year for controlled diabetic patients | Not Covered | Not specified in policy data | Requires documentation of clinical exception to exceed frequency |
| Glycated protein more than monthly for pregnant diabetic women | Not Covered | Not specified in policy data | Hard limit per NCD 100 |
CMS Glycated Hemoglobin Billing Guidelines and Action Items 2026
These are the steps your billing team and clinical staff need to take now, before more claims go out the door under the updated NCD 100.
| # | Action Item |
|---|---|
| 1 | Audit your frequency by patient. Pull a report of all Medicare patients who received A1c or fructosamine tests in the past six months. Flag any patient billed more than four times in the prior twelve months. For each flagged patient, confirm the chart supports a documented clinical exception — altered regimen, intercurrent event, or uncontrolled diabetes. |
| 2 | Update your documentation prompts for ordering providers. If your EHR has order sets for A1c or fructosamine, add a field requiring the ordering provider to document the clinical indication when testing frequency exceeds quarterly. "Routine diabetes monitoring" is not sufficient for anything beyond four tests per year. |
| 3 | Separate your pregnant diabetic patient population in your billing workflow. Glycated protein billing for this group follows a different rule — monthly is the ceiling. Make sure your charge capture reflects that and that the diagnosis supports the order. |
| 4 | Flag patients with hemoglobinopathies or hemolytic anemia. These patients should be billed for glycated protein, not glycated hemoglobin, when interference has been documented. If your lab is flagging interference but your billing team is still submitting A1c claims, you have a claim denial risk and a potential overpayment issue. |
| 5 | Review your medical necessity documentation standards now. The effective date of March 7, 2026 means CMS can apply this updated policy to claims submitted on or after that date. If you're not sure your documentation practices meet the standard for exception cases, talk to your compliance officer before submitting additional claims that exceed the standard frequency limits. |
| 6 | Don't assume no prior auth means no review. Glycated hemoglobin billing doesn't require prior authorization under NCD 100, but Medicare Administrative Contractor (MAC) auditors use NCDs as the basis for post-payment review. High-frequency billers in this category are audit targets. Your reimbursement is at risk retroactively, not just prospectively. |
| 7 | Confirm your lab is communicating interference findings to ordering physicians. The policy specifically notes that when a glycated hemoglobin assay shows potential analytical interference, the lab should inform the ordering physician. If your lab isn't doing this consistently, that's a process gap with both clinical and billing implications. |
| Previous Version | Current Version |
|---|---|
| Coverage is considered experimental and investigational for all indications | Coverage is considered medically necessary when specific criteria are met |
| Prior authorization is not required | Prior authorization is required for initial treatment |
| Documentation must include clinical history | Documentation must include clinical history |
| Re-review every 24 months | Re-review every 12 months with updated clinical documentation |
CPT, HCPCS, and ICD-10 Codes for Glycated Hemoglobin/Glycated Protein Under NCD 100
The published NCD 100 policy data does not include specific CPT, HCPCS, or ICD-10 codes. This is not unusual for older NCDs — code-level specificity is often handled at the local coverage determination (LCD) level by individual MACs.
What This Means for Your Billing Team
Do not assume code-level guidance is absent — it may exist in your MAC's LCD or billing guidelines for laboratory services. Check with your MAC directly, or search your MAC's coverage database for the applicable CPT codes associated with hemoglobin A1c and fructosamine testing.
Commonly associated codes in clinical practice for this test category — not confirmed by the NCD 100 policy data — include the A1c and fructosamine CPT range. Your billing team should confirm the exact codes with your MAC or coding consultant before submitting claims. Do not use codes based on this blog post alone.
If the policy data is updated to include specific codes, PayerPolicy will reflect that in the version diff for NCD 100-v1.
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