Insulin IgG antibodies
| Category | Immunology |
|---|---|
| Test background |
Insulin antibodies can be measured together with other markers of islet cell autoimmunity (GAD65, IA2, ZNT8 antibodies) to predict the development and aid in the diagnosis of type 1 diabetes mellitus (T1DM). Two or more antibodies in combination increase the predictive value of disease development. Of these, insulin and GAD65 antibodies usually arise first. Insulin autoantibody development peaks at 1-2 years of age and is associated with the HLA DR4/DQ8 haplotype (Katsarou, A, et al. Type 1 diabetes mellitus. Nat Rev Dis Primers 3, 17016 (2017)). Screening for diabetic autoantibodies is also used to distinguish between type 2 diabetes mellitus (T2DM) and latent autoimmune diabetes in adults (LADA) in the adult population. Insulin antibodies can also develop following insulin treatment and can be a cause of resistance to insulin. NICE Guidelines for the diagnosis of T1DM in adults (NG17) recommend measuring diabetes-specific autoantibodies at diagnosis and state that the false negative rate can be reduced if quantitative tests for two different diabetes specific antibodies are measured. The laboratory performs quantitative GAD65 and IA2 in house, where these are negative insulin antibodies may be requested. |
| Clinical Indications |
Differential diagnosis of T2DM and LADA |
| Reference range | Negative |
| Sample & container required | Serum RST (rust top) |
| Sample volume | 5-10 mL blood (1 mL serum) |
| Turnaround time | 28 days |
| Notes | Not currently performed in house; this test is referred to the Protein Reference Unit (PRU) in Sheffield. |