CPT code 83036: Hemoglobin A1c testing

What is CPT code 83036?

The 83036 CPT code, as designated by the American Medical Association, is used to report Hemoglobin A1c (HbA1c) testing, a lab test that measures average blood glucose levels over the past two to three months. It assesses how well blood sugar is being controlled in patients with diabetes and is considered a critical marker for monitoring treatment efficacy and long-term risk of complications.

This test is essential for the diagnosis and management of various forms of diabetes, including chemical-induced diabetes mellitus, other specified diabetes mellitus, and conditions related to diabetic chronic kidney disease, moderate and severe nonproliferative diabetic retinopathy, stable proliferative diabetic retinopathy, and diabetic macular edema. By analysing glycated red blood cell proteins, this test provides a reliable view of glycemic control, helping guide therapeutic decisions for both Type 1 and Type 2 diabetes patients.

Documentation requirements

Accurate and complete documentation is essential for CPT code 83036 to meet medical necessity criteria and ensure compliance with payer policies, especially when billing for diabetes management under Medicare or commercial plans. The documentation should include:

Ordering physician’s name and signature

A valid order from a licensed provider (physician, nurse practitioner, or physician assistant) must be in the medical record or lab requisition. This confirms the provider's intent to evaluate glycemic control for diagnostic or monitoring purposes.

Patient identification and date of service

Include the patient’s full name, date of birth, medical record number, and the date the test was performed to correctly match lab results to the individual and support claim accuracy.

Clinical indication for the test

The medical record should clearly state why the HbA1c test was ordered—e.g., for ongoing monitoring of other specified diabetes mellitus, evaluation of treatment changes, or assessment of diabetic chronic kidney disease, diabetic macular edema, or severe nonproliferative diabetic retinopathy.

Appropriate ICD-10 diagnosis codes

Use precise diagnosis codes that reflect the patient's condition. Examples include:

• E11.9: Type 2 diabetes mellitus without complications
• E11.29 Type 2 diabetes mellitus with other diabetic kidney complication
• E11.319 Type 2 diabetes mellitus with unspecified diabetic retinopathy without macular edema
• E09.9: Drug or chemical-induced diabetes mellitus without complications

Test results and interpretation

The lab report should document the A1c value (%) and note whether it is within the target range. If possible, note the clinical interpretation or relevance to ongoing diabetes care.

Frequency and medical justification

If the test is performed more frequently than once every three months (Medicare standard), documentation must justify the need (e.g., medication adjustment, recent change in glucose control, or suspected deterioration in health).

Billing guidelines

Correct billing for CPT 83036 helps avoid claim denials, supports accurate reimbursement, and ensures compliance with Medicare and payer-specific policies. Below are key billing practices and reimbursement guidelines to follow:

Use CPT code 83036 for immunoassay-based HbA1c testing

This code applies when the test uses a standard laboratory method that relies on immunoassay.  For glycated hemoglobin (A1c) testing performed with an FDA-cleared device for home use, provide CPT code 83037 instead.

Report once per testing date

Bill 83036 only once per patient per date of service, even if the patient has multiple diabetic conditions or comorbidities. Do not unbundle or repeat the code unnecessarily.

Watch for frequency limitations

Many payers, including Medicare, allow HbA1c testing up to every 3 months for patients with diabetes. More frequent testing may be allowed, but it must be supported by documentation explaining the need.

Use the appropriate place of service and modifiers if applicable

Ensure the testing location (e.g., office, lab, hospital) is accurately reflected. If only the professional component is billed (interpretation), use modifier 26. If the technical component (lab processing) is billed separately, use modifier TC. If billing globally (entire service), no modifier is needed.

Other relevant CPT codes

• 83037: Glycated hemoglobin (A1c) testing performed with an FDA-cleared device for home use
• 82947: Glucose, quantitative (blood)
• 82962: Glucose, blood by glucose monitoring device(s), non-automated