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Test Code DBS1 Diabetes Mellitus Type 1 Evaluation, Serum

Useful For

Distinguishing type 1 from type 2 diabetes mellitus

 

Identifying individuals at risk of type 1 diabetes (including high-risk relatives of patients with diabetes)

 

Predicting future insulin requirement treatment in patients with adult-onset diabetes

Profile Information

Test ID Reporting Name Available Separately Always Performed
DMEI Diabetes Interpretation, S No Yes
GD65S GAD65 Ab Assay, S Yes Yes
INAB Insulin Abs, S Yes Yes
IA2 IA-2 Ab, S Yes Yes
EZNT8 ZnT8 Ab, S Yes Yes

Method Name

GD65S, INAB, IA2: Radioimmunoassay (RIA)

EZNT8: Enzyme-Linked Immunosorbent Assay (ELISA)

DMEI: Interpretive Comments

Reporting Name

Diabetes Mellitus Type 1 Evaluation

Specimen Type

Serum


Specimen Required


Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 4 mL

Collection Instructions: Centrifuge and aliquot serum into a plastic vial.


Specimen Minimum Volume

2 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  72 hours

Reference Values

GLUTAMIC ACID DECARBOXYLASE (GAD65) ANTIBODY

≤0.02 nmol/L

Reference values apply to all ages.

 

INSULIN ANTIBODIES

≤0.02 nmol/L

Reference values apply to all ages.

 

ISLET ANTIGEN 2 (IA-2) ANTIBODY

≤0.02 nmol/L

Reference values apply to all ages.

 

ZINC TRANSPORTER 8 (ZnT8) ANTIBODY

< 15.0 U/mL

Reference values apply to all ages.

Interpretation

Seropositivity for 1 or more islet cell autoantibodies is supportive of:

-A diagnosis of type 1 diabetes. Only 2% to 4% of patients with type 1 diabetes are antibody negative; 90% have more than 1 antibody marker, and 70% have 3 or 4 markers.(1) Patients with gestational diabetes who are antibody seropositive are at high risk for diabetes postpartum. Rarely, diabetic children test seronegative, which may indicate a diagnosis of maturity-onset diabetes of the young in clinically suspicious cases.

-A high risk for future development of diabetes. Among 44 first-degree relatives of patients with type 1 diabetes, those with 3 antibodies had a 70% risk of developing type 1 diabetes within 5 years.(2)

-A current or future need for insulin therapy in patients with diabetes. In the UK Prospective Diabetes Study, 84% of those classified clinically as having type 2 diabetes and seropositive for glutamic acid decarboxylase 65 (GAD65) required insulin within 6 years, compared to 14% that were antibody negative.(3)

Clinical Reference

1. Bingley PJ. Clinical applications of diabetes antibody testing. J Clin Endocrinol Metab. 2010;95(1):25-33

2. Bingley PJ, Gale EA. Progression to type 1 diabetes in islet cell antibody-positive relatives in the European Nicotinamide Diabetes Intervention Trial: the role of additional immune, genetic and metabolic markers of risk. Diabetologia. 2006;49(5):881-890

3. Turner R, Stratton I, Horton V, et al. UKPDS 25: autoantibodies to islet-cell cytoplasm and glutamic acid decarboxylase for prediction of insulin requirement in type 2 diabetes. UK Prospective Diabetes Study Group. Lancet. 1997;350(9087):1288-1293

4. Thomas NJ, Jones AG. The challenges of identifying and studying type 1 diabetes in adults [published online ahead of print, 2023 Sep 20]. Diabetologia. 2023;10.1007/s00125-023-06004-4. doi:10.1007/s00125-023-06004-4

Day(s) Performed

GAD65 antibody: Monday through Friday

Insulin antibodies: Monday, Wednesday, Friday

IA-2 antibody, Zinc Transporter 8 Antibody: Tuesday, Thursday

Report Available

7 to 10 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

See Individual Test IDs

CPT Code Information

86337

86341 x3

LOINC Code Information

Test ID Test Order Name Order LOINC Value
DBS1 Diabetes Mellitus Type 1 Evaluation 104673-9

 

Result ID Test Result Name Result LOINC Value
81596 GAD65 Ab Assay, S 30347-9
89588 IA-2 Ab, S 81155-4
8666 Insulin Abs, S 60463-7
34268 Diabetes Interpretation, S 69048-7
64926 ZnT8 Ab, S 76651-9