Why is my Doctor Checking for Antibodies

I Have Diabetes, not an Infection!

By Armand A. Krikorian, MD

Insulin is the main hormone that controls your blood sugar (glucose). Cells in the pancreas called islet [EYE-let] cells secrete insulin.

Antibodies are proteins made by your immune system to defend against foreign substances. Sometimes antibodies can be directed against your own body organs. This results in diseases that are called “autoimmune.” Type 1 diabetes is one such disease where antibodies are made against the body’s own islet cells. These antibodies can be detected by blood tests. Several antibodies against the pancreas are islet-cell antibodies (ICA), anti-glutamic [anti-gloo-TAM-ic] acid decarboxylase [dee-kahr-BOK-suh-leyz] antibodies (anti-GAD) and Insulin autoantibodies (IAA).

Type 1 diabetes results from the destruction of insulin producing pancreatic islet cells. The pancreatic antibodies, however, do not cause type 1 diabetes. They simply happen to be present in people at risk of developing type 1 diabetes. They can be detected years before diabetes begins. Doctors can use the antibody levels in the blood to predict who will develop type 1 diabetes. This is still mostly done in research studies, especially in research aimed at preventing the onset of type 1 diabetes.

Not all people with type 1 diabetes have these antibodies, because these antibodies can disappear after years of diabetes being present. So not having these antibodies doesn’t mean you don’t have type 1 diabetes. Presence of the antibodies can help doctors distinguish between type 2 diabetes or type 1 diabetes. This is particularly true in people who might seem to have type 2 diabetes (develop diabetes later in life, have a family history of diabetes, have had diabetes during pregnancy) but do not have the typical body appearance at presentation (are lean), or do not respond to oral pills used for the treatment of diabetes when the diagnosis is not clear. Also, more and more children with newly discovered high blood sugars are being tested for antibodies, because many youth have diabetes that requires only a pill to treat or diet! Young children often are thought to have type 1 diabetes and are started on insulin right away. Clearly, antibody testing can make a huge difference to quality of life for the child and parent.

“Can I be genetically more at risk of having pancreas antibodies?”

Type 1 diabetes is hereditary in only 20% of people. This means that for 80% of people diagnosed with type 1 diabetes, it likely wasn’t hereditary. There are certain gene patterns that have been associated with a higher versus lower risk of developing type 1 diabetes. Researchers are trying to find these gene patterns, because they can be useful when antibody levels are borderline and not strongly positive. We still do not know what triggers antibodies to form in pancreatic tissue. It is unclear if some specific genes cause antibodies to be produced.

“Can I do something to change my pancreatic antibody levels?”

There is no medicine on the market that can make the pancreatic antibodies disappear. There are many promising trials of drugs that perhaps in the future might be used to prevent type 1 diabetes, but these are still in very early stages of testing. Diet and exercise are very important in the treatment of diabetes, but they have no impact on the antibody levels.

“Does a higher level of antibodies mean more severe disease?”

No, the antibodies are considered either positive or negative. Higher or lower levels do not mean more severe diabetes. Also, higher levels do not mean that the diabetes will be more difficult to treat. There is usually no need to follow the levels of antibodies over time as they do not change the way diabetes is managed.

“Are there other diseases that are associated with pancreatic antibodies?”

There is a less common form of diabetes called latent autoimmune diabetes in adults (LADA). With LADA, people affected can also have positive pancreatic antibodies. LADA, also called “slow-onset type 1 diabetes” is a form of type 1 diabetes that typically occurs in people over 30 years old. People with LADA will likely need insulin, and there is data that suggests that these people should be started on very low doses of insulin early to protect the pancreas’ own insulin production.

“Are pancreatic antibodies found in diseases other than diabetes?”

Pancreatic antibodies are associated only with diabetes. However, there is evidence that people with one autoimmune disease are at risk for getting another one. As such, people with type 1 diabetes may also develop other autoimmune diseases, such as autoimmune thyroid disease, celiac [SEE-lee-ack] disease (antibodies to wheat product gluten in the diet), or rheumatoid arthritis. Still, many people with type 1 diabetes do not develop any other autoimmune disease, even if they have positive antibodies to other organs.

“I have taken non-human insulin in the past. What are anti-insulin-binding antibodies?”

Before 1982, insulin in the market was mostly from animals (cows or pigs). Now, all insulin on the market is of human origin. Insulins made from cows or pigs are considered foreign substances by the human body. Many people who received them developed antibodies to insulin called “anti-insulin binding antibodies.” These antibodies can be measured and can interfere with the treatment of diabetes. The newer insulins are nearly identical to the human insulin and rarely cause antibodies to form.

There is much ongoing research on pancreatic antibodies, and many questions need to be answered. As more is learned and understood about what happens in the body to develop type 1 diabetes, there is promise of treatments to actually prevent type 1 diabetes in high-risk people, and to hopefully cure type 1 diabetes in newly diagnosed people. In the meantime, continue to focus on your diabetes through keeping your sugars as near normal as safely possible, keeping your blood pressure and cholesterol under control, and keeping as healthy as possible to decrease the risk of diabetes complications.

Dr. Armand Krikorian is Assistant Professor of Endocrinology and Associate Program Director of the Internal Medicine Residency Program at Case Medical Center and the Louis Stokes VA Medical Center. He has published in multiple journals including the Lancet and is involved in clinical research, education and direct patient care.