Providing information for patients and professionals on research and clinical care in genetic types of diabetes.

Glutamic Acid Decarboxylase (GAD65), Insulinoma Antigen 2 (IA-2) & Zinc Transporter 8 (ZnT8) Autoantibody Testing

Diagnostic Testing for Glutamic Acid Decarboxylase (GAD65 Ab), Insulinoma Antigen 2 (IA-2) & Zinc Transporter 8 (ZnT8) autoantibodies is Now Available at the Royal Devon and Exeter NHS Foundation Trust

Autoantibodies recognizing the islet cell antigens glutamic acid decarboxylase (GAD65), insulinoma antigen 2 (IA-2) and Zinc Transporter 8 (ZnT8) are present in up to 90% of newly diagnosed patients with type 1 diabetes (Wenzlau et al 2007 Proc Natl Acad Sci U S A 104: 17040-17045).  The prevalence of GAD, IA-2 & ZnT8 autoantibodies is less than 1% in GCK, HNF1A and HNF4A MODY, and testing for these autoantibodies close to diagnosis gives very good discrimination of Type 1 diabetes from MODY (McDonald et al 2011 Diabet Med 28: 1028-1033).  The Immunology department at the Royal Devon & Exeter Hospital offers a highly sensitive, automated ELISA method for the quantitative determination of GAD, IA-2 & ZnT8 autoantibodies in both serum and plasma samples.

RSR GAD65 autoantibody ELISA Kit
RSR IA-2 autoantibody ELISA Kit
RSR ZnT8 autoantibody ELISA Kit

REFERENCE RANGE: Refer to report or laboratory.


Clotted blood (1 x 7.5ml) for GAD and IA-2 testing only: Please send with your local Pathology request form and a completed GAD, IA-2 & ZnT8 requestor form to the Immunology Laboratory at the address below.

EDTA blood (minimum 10ml adults; 5ml children; 1ml neonates) for GAD, IA-2, ZnT8 and molecular genetic testing: Please send with a completed MODY request form to the Molecular Genetics Laboratory at the address below.

TRANSPORT OF SPECIMEN: First class post at room temperature


COST: £29.04



Richard Brown
Immunology Laboratory
Area A2
Royal Devon & Exeter Hospital
Barrack Road

Phone: 01392 402464



Sian Ellard
Molecular Genetics Laboratory
RILD Building
Royal Devon & Exeter Hospital
Barrack Road

Phone: 01392 408229

Fax: 01392 408388




    1. Brooking H, Ananieva-Jordanova R, Arnold C, Amoroso M, Powell M, Betterle C, Zanchetta R, Furmaniak J, Smith BR. A sensitive non-isotopic assay for GAD65 autoantibodies. Clin Chim Acta. 2003 May; 331(1-2):55-9.
    2. Nilson E, Ekholm B, Rees Smith B, Törn C, Hillman M. Calcium addition to EDTA plasma eliminates falsely positive results in the RSR GADAb ELISA. Clin Chim Acta. 2008 Feb; 388(1-2):130-4.
    3. A comparison of serum and EDTA plasma in the measurement of glutamic acid decarboxylase autoantibodies (GADA) and autoantibodies to islet antigen-2 (IA-2A) using the RSR radioimmunoassay (RIA) and enzyme linked immunosorbent assay (ELISA) kits. Rahmati K, Lernmark A, Becker C, Foltyn-Zadura A, Larsson K, Ivarsson SA, Törn C. Clin Lab. 2008; 54(7-8):227-35.
    4. McDonald TJ, Colclough K, Brown R, Shields B, Shepherd M, Bingley P, Williams A, Hattersley AT, Ellard S. 2011. Islet autoantibodies can discriminate maturity-onset diabetes of the young (MODY) from Type 1 diabetes. Diabet Med 28:1028-1033.
    5. Wenzlau JM, Juhl K, Yu L, Moua O, Sarkar SA, Gottlieb P, et al. The cation efflux transporter ZnT8 (Slc30A8) is a major autoantigen in human type 1 diabetes. Proc Natl Acad Sci USA 2007;104: 17040–5.