Insulin Autoantibodies

Type 1 diabetes mellitus (T1D) is an autoimmune disease that results from the cell-mediated destruction of islet beta cells. Approximately 12,000 to 15,000 children and adults annually develop T1D. The most recent Standards of Medical Care in Diabetes, supports testing for islet cell autoantibodies to facilitate the early diagnosis of T1D. Early diagnosis can reduce the rate of diabetic ketoacidosis and its associated morbidity and mortality. 

The onset of T1D is preceded by the synthesis of autoantibodies to insulin and islet cell antigens. Detection of one or more islet cell autoantibodies is a strong predictor for progression to type I diabetes. The five-year cumulative risk for developing diabetes has been estimated to be 17% if seropositive for 1 antibody, 39% if seropositive for 2 antibodies, and 70% if seropositive for 3 antibodies. These autoantibodies can often be detected by age 3. 

Presently, four autoantibodies to islet cell antigens have been discovered: insulin, insulinoma associated 2 antigen, glutamic acid decarboxylase 65 (GAD65) and zinc cation efflux transporter 8 (ZnT8).  Individual sensitivities of these autoantibodies for diagnosis of type 1diabetes are 91% for GAD65 antibody, 74% for IA-2 antibody, and 49% for insulin antibody. Together, the combined sensitivity increases to 96%, with a specificity of 98%.

Detection of insulin antibodies in a patient who has never been treated with insulin is consistent with predisposition to T1D. Detection of insulin antibodies is not as informative in patients who have already received insulin therapy because antibody can arise secondary to treatment.

Reference range is 0-5 uU/mL. 

Specimen requirement is one serum gel tube of blood.

For more information see article entitled: “Islet Cell Antibodies.”

References

American Diabetes A. (2) classification and diagnosis of diabetes. Diabetes Care 2015;38 Suppl:S8–S16.

Insel RA, et al. Staging presymptomatic type 1 diabetes: A scientific statement of JDRF, the Endocrine Society, and the American Diabetes Association. Diabetes Care 2015;38:1964–74

Schlosser M, Mueller PW, Torn C, et al. Participating L. Diabetes antibody standardization program: Evaluation of assays for insulin autoantibodies. Diabetologia 2010;53:2611–2