Also called: Insulin Sensitivity
An insulin allergy is an allergic response to an insulin medication. Insulin is a hormone normally produced by the pancreas that is taken via injection or other means by some people with diabetes. People whose bodies do not produce insulin or cannot use it properly may be prescribed insulin to regulate their glucose (blood sugar) levels.
Some people have an allergic response to insulin medication, although it occurs rarely.
An allergy occurs when the immune system identifies a harmless substance as being dangerous and produces antibodies to fight the substance. For some people with insulin allergies, the allergy goes undetected until they suffer an allergic reaction.
Insulin allergies occur because injectable insulin is not exactly the same as naturally produced human insulin. Insulin medication in the United States is almost exclusively a form that is genetically engineered to resemble natural human insulin. The chemical makeup of these human insulins is often modified slightly to change the duration of the insulin action. Rarely insulin from animal sources is used to treat diabetes. Allergic reactions are reactions to these differences, as well as the additives, bacteria and impurities that are present in synthetic human and animal-derived insulin. Insulin allergies are more common with insulin made from animals than with synthetic human insulin.
Allergic reactions associated with the use of insulin can be local (appearing around the injection site) or can affect two or more body systems (anaphylaxis). A local allergic reaction may cause itching, redness or swelling at the injection site. Anaphylaxis may cause breathing difficulty, rash and a drop in blood pressure. Without immediate emergency treatment, anaphylaxis can quickly progress to anaphylactic shock and become deadly.
If the patient must keep taking insulin (e.g., anyone with type 1 diabetes and some people with type 2 diabetes and other forms of diabetes), a physician may treat an insulin allergy with desensitization. Desensitization is the process of reducing or eliminating a patient’s sensitivity to an allergen.
About insulin allergy
An insulin allergy is an allergic response to insulin medication. Insulin is a hormone normally produced by the pancreas to regulate glucose (blood sugar) levels. Insulin is sometimes taken in medication form because some people’s bodies do not produce it, cannot produce enough of it or cannot use it properly. All patients with type 1 diabetes and some people with type 2 diabetes, gestational diabetes and other forms of diabetes (e.g., maturity-onset diabetes of the young) require insulin to manage their glucose levels.
Methods of insulin administration include syringe injections, insulin pumps, insulin pens and jet injectors. In 2006 the U.S. Food and Drug Administration approved the first form of inhaled insulin, a powder that is delivered via an inhaler through the mouth to the lungs. Other methods are being developed, including skin patches, pills and insulin sprayed through the nose.
Some people have an allergic response to insulin medication, although this reaction occurs rarely. An allergic reaction occurs when the body mistakenly perceives the drug as a threat. As a result, the immune system steps up to protect the body from the perceived threat and produces a specific type of antibody to later recognize that allergen. These antibodies flow through the bloodstream and eventually attach themselves to mast cells, which contain a variety of chemicals, including histamines. The antibodies then wait for another encounter with the allergen.
This process of sensitizing a person to an allergen usually takes seven to 10 days. However, it does not produce any allergic symptoms. People do not become aware that this process has occurred until the next time they encounter that allergen. At that time, a chain of reactions including the release of histamine will occur, and allergy symptoms will appear.
The allergic reactions associated with the use of injectable insulin include:
- Local (only in the area where the insulin was injected)
- Anaphylaxis (affecting two or more body systems)
Inhaled insulin appears to produce a greater antibody response than injected insulin, according to recent research. Yet inhaled insulin was not found to increase allergic reactions or other medical complications such as hypoglycemia or lung dysfunction. Additional studies are under way to assess the long-term safety of inhaled insulin.
In the past, the most commonly used insulin was derived from the pancreases of cows and pigs. The insulin produced in cows and pigs is similar to the insulin produced in the human body. The only difference is in the sequence of a few of the amino acids that compose the insulin molecule. This small difference is enough to trigger an allergic reaction in some people. As a result, most people today use synthetic human insulin.
Synthetic human insulin is produced by genetic engineering. It is nearly identical to the insulin naturally produced in the body and it is less likely to cause an allergic response. However, complications are also rare in patients who take animal-derived insulin.
Sometimes patients who suffer allergic reactions from an insulin injection are not allergic to the insulin molecule but are responding to the additives in the insulin. All forms of insulin medication have added ingredients, according to the American Diabetes Association. These additives are used to prevent the growth of bacteria and mold, to preserve the insulin and to maintain the balance of acids and bases. Intermediate-acting insulin and long-acting insulin also contain additives such as zinc and protamine, which cause the body to absorb the insulin at a slower rate.
The bacteria and impurities present in insulin can cause allergic responses. However, technological advances have improved the purity of insulin. Synthetic human insulin is especially pure because it is not combined with other proteins.
In some situations, the reaction is triggered by something other than the insulin. The substances found in insulin vials and syringes, including rubber or latex tops, can induce allergic reactions. Skin-cleansing agents can also cause a reaction.
Insulin allergies are more common in patients with a history of interrupted insulin therapy. The allergy usually appears within one to two weeks after the therapy is resumed.
Not all reactions to insulin are allergic reactions. Sometimes reactions are simply side effects of the medication that do not involve the formation of antibodies.
Signs and symptoms of insulin allergy
Insulin allergies, although rare, are unpredictable and can occur at any time during treatment. Symptoms of an allergic reaction can be immediate or can appear after the patient has been taking the medication for longer than a week. Reactions can either be local or affect two or more body systems (anaphylaxis).
The signs and symptoms of a local allergic reaction to insulin include:
- Dents under the skin at the injection site
- Swelling at the injection site
- Persistent or temporary redness at the injection site
- Itching at the injection site
- Clusters of small bumps that are similar to hives
Local reactions occur only in the area where the insulin was injected. These reactions usually appear within 30 to 60 minutes and usually disappear within a few days to a few weeks. Patients should contact their physician when they believe they are suffering a local allergic reaction to their insulin.
In severe cases an anaphylactic reaction could occur. Anaphylaxis is a rare, severe allergic reaction that affects two or more body systems. It can affect the skin, lungs, nose, throat, gastrointestinal tract and heart. Without prompt emergency treatment, anaphylaxis can quickly progress to anaphylactic shock and become deadly.
Symptoms of anaphylaxis generally occur immediately after exposure to the allergen. However, it can take as long as several hours after exposure before signs of anaphylaxis appear. The more rapidly symptoms appear, the more severe they are likely to become.
Early signs and symptoms include:
- Severe itching of the eyes and face
- Rapid or weak pulse
- Swelling of the throat or tongue
- Slurred speech
- Difficulty swallowing
- Coughing, choking, wheezing or difficulty breathing
- Bluish tint to skin (cyanosis), including lips or nail beds
- Nasal congestion
- Red or swelling skin
- Hives (including on the lips, eyelids, throat and tongue)
- Abdominal cramps
- Nausea or vomiting
- Drop in blood pressure
- Collapse or loss of consciousness
- Loss of bladder control
- Cardiac arrest
- Respiratory arrest
Patients should ask their physician what steps to take if they recognize any of these symptoms. A common recommendation is to seek emergency treatment as soon as an insulin-using diabetic person experiences any of the signs or symptoms of a systemic allergic reaction.
Diagnosis and treatment
For many people with insulin allergies, the allergy goes undetected until they suffer an allergic reaction. The first goal of treatment generally is to relieve the symptoms of a local allergic reaction and to prevent anaphylactic shock if a severe reaction is occurring. Diabetic individuals using insulin should consult their physician to assess their risk of insulin allergy and the appropriate response if such an occurrence is suspected.
Some of the typical approaches to an allergic reaction include administering an antihistamine, which may be given to relieve mild symptoms, such as itching and rash. Antihistamines are a group of drugs that block the effects of histamine, a chemical released during an allergic reaction.
Corticosteroid cream or tablets may be recommended when skin rashes fail to clear up. Corticosteroids are a group of anti-inflammatory and immunosuppressive drugs similar to hormones produced by the body. In patients with asthma-like symptoms, such as wheezing or cough, a bronchodilator may be prescribed. Bronchodilators are a group of drugs used to widen the lungs’ airways (bronchi).
In cases of anaphylaxis, treatment is frequently an injection of epinephrine. Epinephrine constricts the blood vessels, prevents fluid leakage, opens the airways and raises blood pressure. It also quickly relieves the itching and skin flushing that is part of most episodes of anaphylaxis.
Patients with a history of severe reactions may have a prescribed epinephrine injection kit to treat themselves in an emergency. These patients may be advised in advance by their physician to administer their shot while someone else calls for emergency help. Those who do not have access to epinephrine must seek emergency treatment immediately. Epinephrine may then be administered in an emergency room or by emergency personnel.
To diagnose an insulin allergy, a physician will ask patients about their medical history and perform a physical examination.
Symptoms and a history of allergies to medications are usually enough to diagnose an insulin allergy. A physician may order an allergy skin test to determine if any form of insulin can be tolerated. A variety of insulin types can be introduced to the skin. The test is positive if the skin shows a reaction.
When a patient reacts to all types of insulin, a physician may recommend desensitization. Desensitization is the process of reducing or eliminating a patient’s sensitivity to an allergen. This is accomplished over time by injecting the patient with small but increasing amounts of the allergen. Desensitization is a risky procedure and is considered only in cases when there are no alternative medications or therapies available.
The insulin type that triggered the smallest allergic reaction is usually used in the desensitization process. After the first dose is introduced, the patient is asked to wait a specific time period until the next dose. Increasing doses of insulin are given over a period of minutes or hours to days, until the usual therapeutic dose is tolerable. The patient is monitored for some time after each dose to ensure that a significant allergic reaction is not occurring. Allergic reactions can occur at any time, even when the previous doses did not trigger a reaction. Should allergy symptoms appear during the desensitization therapy, allergy medications (e.g., antihistamines, corticosteroids or epinephrine) may be administered to relieve the symptoms.
There is no known way to prevent the development of an insulin allergy. However, patients may be advised by their physician to avoid discontinuing insulin therapy because insulin allergies are more common in patients with a history of interrupted insulin therapy.
Questions for your doctor
Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about insulin allergy:
- Do I or could I have an insulin allergy?
- What signs should I watch for?
- What diagnostic tests might I need?
- Could I instead be allergic to latex or something else used in my administration of insulin?
- If I’m allergic to my insulin, can I be treated with something other than insulin?
- If not, could a different type of insulin help me?
- Am I candidate for desensitization therapy?
- Will medications or any other treatment options help me?
- What are the risks of my insulin allergy? What are my chances of developing anaphylaxis or anaphylactic shock?
- Should I carry an epinephrine injection kit in case of an allergic emergency?
- What should be done if I have an allergic emergency?