Type of test Blood

 Normal findings

 < 1:4 titer; no antibody detected

 Test explanation and related physiology

 Type 1 diabetes mellitus (DM) is insulin-dependent (IDDM). It is becoming increasingly recognized that this disease is an organ-specific form of autoimmune disease that results in destruction of the pancreatic islet cells and their products. These antibodies are used to differentiate type I DM from type II non–insulin-dependent DM. Nearly 90% of people with type 1 DM have one or more of these autoantibodies at the time of their diagnosis. People with type 2 DM have low or negative titers. Determining which type of diabetes a patient has is critical in providing the proper care and treatment. However, a rise in childhood obesity has made distinguishing between type 1 and type 2 diabetes increasingly more challenging. Maturity-onset diabetes of the young (MODY) type 3 is important to identify so that treatment can be most appropriately provided.

These antibodies often appear years before the onset of symptoms. The panel is useful to screen relatives of IDDM patients who are at risk of developing the disease. GAD Ab provide confirmatory evidence. The presence of these antibodies identifies which woman with gestational diabetes will eventually require insulin permanently.

 Because identifying the type of diabetes can be complex, DNA molecular testing for NF1A (MODY3), GCK (MODY2), HNF4A (MODY1), and HNF1B (MODY5) is valuable. Defects in these genes are a cause of MODY.

The presence of insulin antibodies is diagnostic of factitious hypoglycemia from surreptitious administration of insulin. This antibody panel is also used in surveillance of patients who have received pancreatic islet cell transplantation. Finally, these anti bodies can be used to identify late onset type 1 diabetes in those patients previously thought to have type 2 diabetes.

Procedure and patient care

• See inside front cover for Routine Blood Testing.

• Fasting: no

 • Blood tube commonly used: red or serum separator

Abnormal findings

 Increased levels

- Insulin-dependent diabetes mellitus

- Insulin resistance

- Allergies to insulin

- Factitious hypoglycemia