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Epic Test Code LAB25232 Diabetes Mellitus Type 1 Evaluation, Serum

Additional Codes

MML:DBS1

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

Highlights

This evaluation consisting of tests for 4 antibodies targeting islet cell antigens (GAD65, IA-2, ZnT8, and insulin) gives optimum sensitivity and specificity for the diagnosis of type 1 diabetes mellitus.

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


Container/Tube: 

Preferred: Red top

Acceptable: Serum gel

Specimen Volume: 4 mL


Bassett Healthcare Network Clinical Laboratories Note:

Blood Tube Draw Volume
Min 50% draw volume  

Specimen Minimum Volume

2 mL

Specimen Stability Information

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

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross reject

Icterus

Mild OK; Gross reject

Other

NA

Clinical Information

Islet cell autoantibodies have been known to be associated with type 1 diabetes mellitus since the 1970s. Since 1988, several autoantigens against which islet antibodies are directed have been identified. These include the insulinoma-associated protein 2 (IA-2), glutamic acid decarboxylase 65 (GAD65), insulin and, most recently, the zinc transporter ZnT8.(1) Only 4% to 7% of patients with type 1 diabetes are autoantibody negative, fewer than 10% have only 1 marker, and around 70% have 3 or 4 markers. These findings have been confirmed in multiple specialty laboratories internationally.

 

One or more of these autoantibodies are detected in 93% to 96% of patients with type 1 diabetes, both adults and children. These antibodies are also detectable in relatives of type 1 diabetic patients at risk for developing diabetes, before clinical onset.(2) Some patients with type 1 diabetes are initially diagnosed as having type 2 diabetes because of symptom-onset in adulthood, societal obesity, and initial insulin-independence. These patients with either "latent autoimmune diabetes in adulthood" or type 1 diabetes mellitus may be distinguished from those patients with type 2 diabetes by detection of 1 or more islet autoantibodies (including ZnT8 antibody). Patients with gestational diabetes can also be stratified for future diabetes risk by detection of 1 or more islet autoantibodies.

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 required insulin within 6 years, compared to 14% that were antibody negative.(3)

Cautions

Negative results do not exclude the diagnosis of or future risk for type 1 diabetes mellitus. The risk of developing type 1 diabetes may be stratified further by testing for HLA genetic markers. Careful monitoring of hyperglycemia is the mainstay for determining the requirement for insulin therapy.

Day(s) and Time(s) Performed

Monday through Thursday, Sunday; 10 p.m.

GAD65 antibody: Monday through Friday; 4 a.m.; 4 p.m.

Insulin antibodies: Monday, Wednesday, Friday; 4 a.m.

IA-2 antibody: Tuesday, Thursday; 4 a.m.

Zinc Transporter 8 Antibody: Tuesday and Thursday, 10 a.m.

Analytic Time

7 days

Specimen Retention Time

28 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

86337-Insulin antibodies

86341 x3-Islet cell antibody

NY State Approved

Yes