Diabetes

Indications for Autoimmune Diabetes Mellitus Insulin Antibody Testing

  • Most useful in establishing autoimmune etiology in previously diagnosed type I DM.
  • Order at least two antibody tests; do not order individual antibody tests.
  • For most cases, use Glutamic Acid Decarboxylase Antibody in combination with one or more of the following: IA-2 Antibody, Zinc Transporter 8 Antibody, Islet Cell Cytoplasmic Antibody, and Insulin Antibody.

Type 1 DM
  • Patient should have diagnosed DM:
    • Antibody testing is not useful for the diagnosis of DM.
    • Testing is not recommended for evaluating autoimmune etiology in patients receiving insulin > two weeks, as insulin antibody formation may occur (false-positive test result possible).
  • Most useful in newly diagnosed DM in children <18 years to establish autoimmune etiology.
  • May be useful in difficult adult cases when it is unclear if patient has type 1 or 2 DM.
Type 2 DM
  • No indication for routine evaluation or management.
Screening
  • Not recommended for screening family members of patients with type 1 DM (risk prediction) except in research settings.
Limited Use
  • Latent autoimmune DM in adults (LADA): differentiates LADA from type 2 DM.
  • Genetic testing: identifies patients with DM for whom a genetic etiology is suspected (e.g., monogenic DM, maturity-onset diabetes of the young [MODY]). Lack of antibodies suggests a genetic disorder.
  • Gestational diabetes mellitus (GDM):
    • Screen women with history of GDM to identify those at high risk for progression to type 1 DM.
    • No evidence to suggest test results alter outcomes or improve care when compared to intermittent hemoglobin A1c testing.

Test Menu

When pursuing antibody testing to determine the presence of autoimmune diabetes mellitus (DM), perform at least two of the following antibody tests:

Test # Test Name
2001771 Glutamic Acid Decarboxylase Antibody (GAD)
0050202 IA-2 Antibody
2006196 Zinc Transporter 8 Antibody
0050138 Islet Cell Cytoplasmic Antibody, IgG
0099228 Insulin Antibody (IAA)*

* Used to determine presence of antibodies to insulin analogues.

Additional Resources