CurrentCapital BlueCrossPolicy AHS G2006

Diabetes mellitus testing (A1c, FPG, OGTT) coverage

Capital BlueCross policy describing indications, coverage criteria, and clinical background for laboratory testing used to diagnose, screen, and monitor diabetes mellitus (HbA1c, fasting plasma glucose, and oral glucose tolerance testing). Affects providers ordering these tests and billing/authorization teams.

Policy Summary

PayerCapital BlueCross

PolicyDiabetes mellitus testing (A1c, FPG, OGTT) coverage

Policy CodePolicy AHS G2006

Change TypeNo material change

Effective DateSep 18, 2015

Next Review DateN/A

Key ActionVerify member benefits and Medicare/Medicaid specifications before applying coverage criteria and use NGSP‑certified, DCCT‑traceable A1c methods (or plasma glucose criteria when A1c is unreliable) with documentation of rationale.

SourceLink

3Primary tests discussed

10+CF-related diabetes OGTT screening begins

≥6.5%Diagnostic A1c threshold for diabetes

≥126Diagnostic FPG threshold

≥200

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OGTT 2-hour diagnostic threshold

2CPT/HCPCS codes listed

When Testing Is Covered

Measurement of plasma glucose (FPG) coverage

Measurement of plasma glucose meets coverage when ANY of the following are present:

ANY of the following

Individual with acute or persistent classic symptoms of diabetes mellitus (e.g., polyuria, polydipsia, nocturia, blurred vision, weight loss)
FPG used for diagnosis

Hemoglobin A1c coverage in individuals with diagnosed diabetes

Measurement of hemoglobin A1c meets coverage when ANY of the following are present for individuals with diagnosed type 1 or type 2 diabetes:

ANY of the following

Upon initial diagnosis to establish baseline and determine treatment goals
Quarterly in individuals meeting treatment goals and who, based on daily glucose monitoring, appear to have stable glycemic control
Quarterly in individuals who are not meeting treatment goals for glycemic control
Quarterly in individuals whose pharmacologic therapy has changed
Quarterly for individuals who are pregnant

OGTT for cystic fibrosis-related diabetes (CFRD) screening

Annual OGTT screening for cystic fibrosis-related diabetes (CFRD) meets coverage when ALL of the following are present:

ALL of the following

Individual has cystic fibrosis
Individual is 10 years of age or older
Age criterion applied below
Individual has not been diagnosed with CFRD

Diagnostic criteria (informational clinical thresholds)

Diagnostic cut points referenced in the policy:

ALL of the following

Fasting plasma glucose (FPG) ≥ 126 mg/dL establishes diabetes in an asymptomatic individual≥ 126 mg/dL
2-hour plasma glucose (2-h PG) during 75 g OGTT ≥ 200 mg/dL establishes diabetes≥ 200 mg/dL
Hemoglobin A1c (A1c) ≥ 6.5% is diagnostic of diabetes≥ 6.5%
A1c 5.7% to <6.5% indicates increased risk (prediabetes)

Diagnostic criteria for diabetes (multiple society recommendations)

Diagnosis of diabetes is met when specified thresholds are reached — confirmatory testing or symptomatic hyperglycemia rules apply as noted.

ANY of the following

Fasting plasma glucose (FPG) ≥ 126 mg/dL (7.0 mmol/L)
2-hour plasma glucose ≥ 200 mg/dL after 75-g OGTT
Random plasma glucose ≥ 200 mg/dL in a person with symptoms of hyperglycemia
A1C ≥ 6.5%

Confirmatory testing

Diagnosis requires two abnormal test results from either the same sample or two separate samples, except when random glucose ≥200 mg/dL with symptoms (then single test confirms diagnosis).

Prediabetes criteria

ANY of the following

Impaired fasting glucose (IFG): FPG 100–125 mg/dL100–125 mg/dL
Impaired glucose tolerance (IGT): 2‑hour PG 140–199 mg/dL on 75-g OGTT140–199 mg/dL
A1C 5.7%–6.4% (A1C recommended for screening but diagnosis should be confirmed with glucose testing)5.7%–6.4%

Gestational diabetes mellitus (GDM) screening and diagnosis

Recommendations include universal screening during pregnancy and use of one-step or two-step diagnostic approaches.

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A1C testing and monitoring guidance

ALL of the following

Use NGSP-certified A1C methods traceable to DCCT; point-of-care A1C devices may be used if FDA-cleared and CLIA requirements are met (personnel, proficiency testing thrice yearly).
Assess glycemic status by A1C and/or appropriate CGM metrics at least twice a year in stable patients; assess quarterly (every 3 months) for patients not meeting goals or with therapy changes.
A1C goals should be individualized; many children: A1C <7% may be appropriate; in pregnancy target <6% if achievable without hypoglycemia, may relax to <7%.
A1C may be unreliable in conditions affecting erythrocyte turnover (pregnancy, hemoglobinopathies, CKD, dialysis) and in people with HIV (A1C may underestimate glycemia).

Screening frequency recommendations

ANY of the following

USPSTF: screen adults 35–70 years with overweight/obesity; screening every 3 years may be reasonable if initial normal.
Diabetes Canada / AACE: screen adults ≥40 (or ≥45 per some guidelines) every 3 years; consider more frequent (annual) screening for high-risk or multiple risk factors.
Endocrine Society: screen patients ≥65 every 2 years.

Perioperative and inpatient glucose management

ALL of the following

Perform A1C on all people with diabetes or hyperglycemia admitted to hospital if no recent A1C available.
In hospitalized patients who are eating, perform POC glucose monitoring before meals; if not eating, monitor every 4–6 hours; IV insulin requires monitoring every 30–120 minutes.
Perioperative glucose target: 100–180 mg/dL within 4 hours of surgery. Do not use CGM alone during surgery. A1C for elective surgery ideally <8% when possible.
Hold metformin on day of surgery; hold other oral agents morning of surgery; adjust insulin dosing (e.g., reduce basal insulin by ~25% evening before surgery); discontinue SGLT2 inhibitors 3–4 days before surgery.

Screening for comorbidities in diabetes

ANY of the following

Consider cardiac evaluation (e.g., natriuretic peptide, echocardiography) in adults with diabetes at risk for heart failure or with abnormal findings.
Screen for peripheral arterial disease with ankle-brachial index in patients with age ≥50 or diabetes duration ≥10 years, microvascular disease, foot complications, or end-organ damage.
Screen adults with type 2 diabetes or prediabetes for clinically significant liver fibrosis (risk stratify using FIB-4), with further evaluation by transient elastography or ELF if indeterminate/high risk; refer high risk to hepatology.

Key Numeric Thresholds and Diagnostic Cutoffs

Clinical thresholds

A1c diagnostic threshold≥ 6.5%

A1c prediabetes range5.7% to <6.5%

Fasting plasma glucose diagnostic threshold≥ 126 mg/dL

Impaired fasting glucose (prediabetes)100–125 mg/dL

OGTT 2-hour diagnostic threshold≥ 200 mg/dL (75 g OGTT)

GDM one-step 75-g OGTT cutoffsFasting ≥92 mg/dL; 1-hour ≥180 mg/dL; 2-hour ≥153 mg/dL (one or more abnormal = GDM)

Peripregnancy early screening fasting glucose110–125 mg/dL (identify abnormal glucose metabolism before 15 weeks)

Procedure / Diagnostic Codes Referenced

Applicable procedure/diagnostic codes discussed (document references testing modalities but does not list explicit CPT/HCPCS/ICD codes in this part)mixed

No codes listed

Applicable CPT/HCPCS Procedure Codes (listed)CPT|HCPCS

82985	Glycated protein_.
83037	Hemoglobin;_glycosylated (ATC)by device cleared by FDA for home use

What Providers Must Do / Watch For

Documentation Required

Use NGSP-certified methods for A1c

A1c testing must be performed using methods certified by the National Glycohemoglobin Standardization Program (NGSP) and traceable to the Diabetes Control and Complications Trial (DCCT) reference assay; point-of-care A1c testing must be FDA-approved and performed in CLIA-certified laboratories meeting CLIA quality standards.

Prior Authorization

Benefit verification required

Verify the member's benefit coverage before ordering tests — coverage determination depends on the individual's benefit plan and any applicable Medicare or Medicaid specifications.

Check Applicable State and Federal Regulations and LCD/NCD guidance when relevant.

Documentation Required

Background and Clinical Context

Diabetes mellitus comprises multiple heterogeneous disorders characterized by hyperglycemia from diverse causes, including autoimmune destruction of pancreatic β-cells (type 1), progressive β-cell failure with insulin resistance (type 2), gestational diabetes mellitus (GDM), and specific forms related to monogenic syndromes, diseases of the exocrine pancreas (e.g., cystic fibrosis, pancreatitis), or drug- and chemical-induced diabetes (e.g., glucocorticoids, some HIV therapies, post-transplant) (types of diabetes). Many people with diabetes are asymptomatic; classic hyperglycemia symptoms include polyuria, polydipsia, nocturia, blurred vision, and weight loss, but routine laboratory testing increasingly identifies cases before symptoms develop. (Source: classification and clinical presentation.)

The three primary laboratory approaches discussed are hemoglobin A1c (A1c), fasting plasma glucose (FPG), and the oral glucose tolerance test (OGTT). A1c reflects average glycemia over the preceding 8–12 weeks and offers greater analytic stability and lower short-term biologic variability than plasma glucose measures; A1c assays standardized to the DCCT/NGSP and IFCC reference systems have good interlaboratory performance when performed with certified methods. However, A1c may be unreliable in conditions that alter erythrocyte turnover or hemoglobin (pregnancy, hemoglobinopathies, recent transfusion, erythropoietin therapy, advanced CKD, some people with HIV), and in those settings plasma glucose criteria are preferred. FPG is measured after ≥8 hours fasting and is convenient for diagnosing type 2 diabetes and prediabetes; OGTT evaluates the 2-hour plasma glucose response to a glucose load and is more sensitive than FPG or A1c for detecting some forms of dysglycemia (for example, CFRD and GDM).

Diagnostic and monitoring implications: standard diagnostic thresholds referenced in this policy include A1c ≥ 6.5% (diabetes) and A1c 5.7%–6.4% (increased risk/prediabetes), FPG ≥ 126 mg/dL (diabetes) with IFG 100–125 mg/dL for prediabetes, and a 2‑hour 75-g OGTT ≥ 200 mg/dL for diabetes. Each test captures different pathophysiology and can be discordant; diagnosis generally requires two abnormal results (same or separate samples) except when random plasma glucose ≥ 200 mg/dL occurs with classic symptoms. (Source: diagnostic thresholds and confirmatory testing.)

Defined Terms

Definitions

A1c (HbA1c)Glycated hemoglobin reflecting average glycemia over previous 8–12 weeks; requires NGSP-certified assay for diagnostic use.

FPGFasting plasma glucose measured after typically ≥8 hours fasting.

OGTTOral glucose tolerance test; typically 75 g glucose with 2-hour plasma glucose measurement (100-g 3-hour used in two-step GDM diagnosis).

CFRDCystic fibrosis-related diabetes.

NGSPNational Glycohemoglobin Standardization Program (certifies A1c methods).

GDMGestational diabetes mellitus — glucose intolerance diagnosed during pregnancy.

IFG

Policy Dates and Review Cycle

Policy Number: AHS G2006. This policy was originally effective 2015-09-18 and the most recent review date noted in the document header is 2025-04-01. No next review date is recorded in the brief.

The brief indicates there is no material change for this version of the policy (has_material_change = false). The header dates and policy number complement the changes list and signal that updates through the 2025 review were incorporated without a material change to coverage stance in this excerpt.

Policy Summary

PayerCapital BlueCross

PolicyDiabetes mellitus testing (A1c, FPG, OGTT) coverage

Policy CodePolicy AHS G2006

Change TypeNo material change

Effective DateSep 18, 2015

Next Review DateN/A

SourceLink

On This Page

Perioperative glucose goal100–180 mg/dL within 4 hours of surgery

CFRD screening/A1c noteA1c ≥6.5% is consistent with CFRD but A1c is not recommended for screening due to low sensitivity

Use plasma glucose when A1c may be unreliable

When conditions known to alter A1c accuracy are present, use plasma glucose criteria for diagnosis and document the clinical rationale.

Conditions include hemoglobin variants, pregnancy, glucose‑6‑phosphate dehydrogenase deficiency, recent transfusion or blood loss, erythropoietin therapy, advanced CKD or dialysis, and HIV.

Documentation Required

OGTT preparation

Before performing an OGTT for screening, ensure the patient has adequate carbohydrate intake (at least 150 g/day) for the three days prior; document preparation when ordering the test.

Adequate carbohydrate intake: at least 150 g/day for three days prior to testing.

Documentation Required

Use NGSP-certified A1C methods and CLIA compliance for POC devices

Ensure A1C testing uses NGSP‑certified, DCCT‑traceable methods; point‑of‑care A1C devices must be FDA‑cleared for intended use and the testing site must meet CLIA personnel and proficiency testing requirements.

Applicable code: 83037
CLIA requirements include specified personnel competency (documented assessments) and participation in proficiency testing three times per year.

Prior Authorization

Not stated in this excerpt

No explicit prior authorization requirements are specified within this document excerpt.

Providers should still verify benefits and payer rules per Applicable State and Federal Regulations.

Documentation Required

Confirmatory testing for diagnosis

When diagnostic results are borderline or only one abnormal value is present, repeat the test or obtain confirmatory testing on a separate day to establish diagnosis, except when symptomatic hyperglycemia with plasma glucose ≥200 mg/dL is present.

A diagnosis may be made from a single test if random plasma glucose ≥200 mg/dL with classic symptoms.

Denial Risk

A1C limitations and interpretation risks

Recognize that A1C may be unreliable in pregnancy, hemoglobinopathies, advanced CKD/dialysis, HIV, and other conditions; misinterpretation can lead to diagnostic or management errors and potential coverage or clinical risks.

Marked discordance between A1C and glucose values should prompt evaluation for test interference.

Documentation Required

GDM postpartum follow-up

For individuals with prior gestational diabetes, document completion of a fasting OGTT at 4–12 weeks postpartum and record an ongoing screening plan for diabetes (every 1–3 years) even if the postpartum OGTT is normal.

Use a fasting OGTT at 4–12 weeks postpartum with nonpregnancy diagnostic criteria.
Ongoing screening may be annual A1C, annual FPG, or triennial OGTT.

Screening guidance follows major society recommendations: the ADA and others recommend risk-based screening beginning in adults (routine screening generally beginning around age 35 for average-risk adults, sooner and more frequently for high-risk individuals), repeat screening at least every 3 years when initial tests are normal (more frequent, e.g., annual, for higher-risk persons), and special pediatric guidance to consider screening after onset of puberty or ≥10 years of age in at‑risk youth. For pregnancy, universal screening for GDM is recommended at 24–28 weeks' gestation, with either a one-step 75-g OGTT or a two-step approach (50-g screening followed by a diagnostic 100-g OGTT if positive); postpartum evaluation with a fasting OGTT at 4–12 weeks is advised, followed by ongoing screening every 1–3 years. (Source: ADA/USPSTF/Diabetes Canada guidance.)

Population impact and prognostic relevance: diabetes prevalence in the U.S. is substantial (CDC estimates cited: ~38.4 million people, with millions more undiagnosed and ~97.6 million adults with prediabetes). Higher A1c levels are associated with progressive risk of microvascular and macrovascular complications and adverse outcomes (e.g., increased stroke and preterm birth risks with rising A1c); visit‑to‑visit A1c variability is also linked to worse outcomes. These epidemiologic and outcome data underpin the value of appropriate selection and frequency of testing. (Source: CDC statistics and outcome studies.)

Limitations of alternative glycemic biomarkers: fructosamine, glycated albumin, and 1,5‑anhydroglucitol reflect shorter-term glycemia and may correlate with glucose trends but have less robust evidence for diagnostic use than A1c. In specific situations such as cystic fibrosis‑related diabetes (CFRD), A1c has low sensitivity for screening and OGTT remains the preferred test; studies show alternative markers and A1c perform poorly compared with 2‑hour OGTT for CFRD detection. When A1c is unreliable or potentially misleading, the policy directs use of plasma glucose criteria and documentation of rationale. (Source: discussion of alternative biomarkers, CFRD findings, and A1c limitations.)

Impaired fasting glucose.

IGTImpaired glucose tolerance.

Diabetes mellitus testing (A1c, FPG, OGTT) coverage

When Testing Is Covered

Key Numeric Thresholds and Diagnostic Cutoffs

Procedure / Diagnostic Codes Referenced

What Providers Must Do / Watch For

Background and Clinical Context

Defined Terms

Other Policies to Review

Policy Dates and Review Cycle