Test ID: DME
Diabetes Mellitus Type 1 Evaluation
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
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 A profile is a group of laboratory tests that are ordered and performed together under a single Mayo Test ID. Profile information lists the test performed, inclusive of the test fee, when a profile is ordered and includes reporting names and individual availability.
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| PAINT | Interpretive Comments | No | Yes |
| GD65S | GAD65 Ab Assay, S | Yes | Yes |
| INAB | Insulin Abs, S | Yes | Yes |
| IA2 | IA-2 Ab, S | Yes | Yes |
Method Name A short description of the method used to perform the test
Radioimmunoassay (RIA)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Specimen Volume: 4 mL
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild OK; Gross reject |
| Lipemia | Mild OK; Gross reject |
| Icterus | Mild OK; Gross reject |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerated (preferred) | 14 days |
| Ambient | 72 hours | |
| Frozen | ||
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Islet cell autoantibodies were first recognized to be associated with type 1 diabetes mellitus in 1974. Several islet cell-specific autoantigens have been identified in recent years.(1) These include glutamic acid decarboxylase 65 (GAD65), the tyrosine phosphatase-related islet antigen 2 (IA-2), and insulin. The sensitivities of these autoantibodies for type 1 diabetes in an international collaborative study were 91% (GAD65 antibody), 74% (IA-2 antibody), and 49% (insulin antibody) when tested in isolation.(2) When tested in combination, the combined sensitivity for type 1 diabetes was up to 98%, with a specificity of 98% to 100%. (2) These autoantibodies also are detectable before the clinical onset of diabetes. Prospective studies in relatives of patients with type 1 diabetes have shown that the detection of 1 or more islet autoantibodies is an early marker of progression to type 1 diabetes. Among first-degree relatives of those with type 1 diabetes, the cumulative risk of developing diabetes at 5 years after testing was 17% if seropositive for 1 antibody, 39% if seropositive for 2 antibodies, and 70% if seropositive for 3 antibodies.(3) Autoantibody profiles identifying patients destined to develop type 1 diabetes are usually detectable in serum before age 3. Some patients with type 1 diabetes are initially misdiagnosed as having type 2 diabetes because of symptom onset in adulthood, societal obesity, and initial insulin-independence. Detection of 1 or more islet autoantibodies allows identification of patients with "latent autoimmune diabetes in adulthood" amongst those with presumed type 2 diabetes.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
GLUTAMIC ACID DECARBOXYLASE (GAD65) ANTIBODY
< or =0.02 nmol/L
Reference values apply to all ages.
INSULIN ANTIBODIES
< or =0.02 nmol/L
Reference values apply to all ages.
ISLET ANTIGEN 2 (IA-2) ANTIBODY
< or =0.02 nmol/L
Reference values apply to all ages.
Interpretation Provides information to assist in interpretation of the test results
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 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 1diabetes, those with 3 antibodies had a 70% risk of developing type 1 diabetes within 5 years.(3)
-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.(4)
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
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 antibody targeting zinc transporter 8 (ZnT8) and HLA genetic markers. Careful monitoring of hyperglycemia is the mainstay for determining the requirement for insulin therapy.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Bingley PJ: Clinical applications of diabetes antibody testing. J Clin Endocrinol Metab 2010;95:25-33
2. Verge CF, Stenger D, Bonifacio E, et al: Combined use of autoantibodies (IA-2 autoantibody, GAD autoantibody, insulin autoantibody, cytoplasmic islet cell antibodies) in type 1 diabetes: Combinatorial Islet Autoantibody Workshop. Diabetes 1998;47:1857-1866
3. 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;49:881-890
4. 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;350:1288-1293
5. Masuda M, Powell M, Chen S, et al: Autoantibodies to IA-2 in insulin-dependent diabetes mellitus. Measurements with a new immunoprecipitation assay. Clin Chim Acta 2000;291:53-66
Method Description Describes how the test is performed and provides a method-specific reference
(125)I-labeled recombinant human antigen (glutamic acid decarboxylase 65, islet antigen 2, or insulin) is added to the test serum. If antibody is present, it forms a soluble complex with the (125)I-labeled antigen. Subsequent addition of goat antihuman IgG and IgM precipitates the complex. The amount of radioactivity in the precipitate is proportional to the level of antibody in the serum.(5)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
GAD65 Antibody: Monday through Thursday, Sunday; 8 a.m.
Insulin Antibodies: Monday, Thursday; 2 p.m.
IA-2 Antibody: Tuesday, Thursday; 10:00 a.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
86337-Insulin antibodies
86341 x 2-Islet cell antibody
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 81596 | GAD65 Ab Assay, S | 30347-9 |
| 89588 | IA-2 Ab, S | In Process |
| 8666 | Insulin Abs, S | 60463-7 |
| 29347 | Interpretive Comments | In Process |
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