Diabetes Mellitus Type 1 Evaluation, Serum

Insulin Antibodies, Islet-cell Antibodies, GAD65 Antibody, Zinc Transporter 8 Antibody, Diabetes Autoimmune Test Group

Test Codes

EPIC: LAB1231966, Beaker: Diab Type 1, Quest: 13621
NOTE: Testing includes:

• Glutamic Acid Decarboxylase 65 Ab
• Insulin Autoantibody
• IA-2 Antibody
• Zinc Transporter 8 (ZnT8) Antibody

Department

Send Outs

Specimen Collection Criteria

Collect (preferred specimen): Two Gold-top SST tubes.
Also acceptable: Two plain Red-top tubes.

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells. Transfer serum to plastic transport tube and maintain at room temperature (20-26°C or 68-78.8°F) prior to transport.

Preparation for Courier Transport

Transport: 4.0 mL serum, room temperature (20-26°C or 68-78.8°F). (Minimum: 2.0 mL)

Rejection Criteria

• Grossly hemolysis.
• Lipemic specimen.
• Icteric specimen.
• Specimens not collected and processed as indicated.

In-Lab Processing

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells. Transfer serum to plastic transport tube and maintain at room temperature (20-26°C or 68-78.8°F) prior to transport.

Transport: 4.0 mL serum, room temperature (20-26°C or 68-78.8°F). (Minimum: 2.0 mL)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 7 days
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 28 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to Quest Diagnostics, Wood Dale, IL.

Performed

Varies.

Reference Range

Glutamic Acid Decarboxylase 65 Ab:  <5 IU/mL
Insulin Autoantibody:  <0.4 U/mL
IA-2 Antibody:  <5.4 U/mL
Zinc Transporter 8 (ZnT8) Antibody:  <15 U/mL

Test Methodology

ELISA and Radioimmunoassay, Radiobinding Assay (RBA)

Clinical Utility

Diabetes Type 1 Autoantibody Panel - The American Diabetes Association supports using autoantibody (AAb) screening to diagnose T1D. T1D autoantibodies are markers of ongoing damage to insulin-producing beta cells. The four AAbs used in clinical practice to diagnose T1D are: AAbs against insulin (IAA), tyrosine phosphatase IA2 (IA2A), glutamic acid decarboxylase (GAD65), and zinc transporter. Numerous clinical trials demonstrate important clinical benefits associated with detecting T1D using an AAb screening approach.

Clinical guidelines have been established to help identify T1D at its earliest phases and before progression to DKA, providing presymptomatic and symptomatic staging of T1D.

CPT Codes

86337, 86341x3.

Contacts

Last Updated

11/25/2025